Archive

Archive for the ‘Fuel Efficiency’ Category

Single File, Please

December 6th, 2009 Comments off
VW L1

Volkswagen L1 Concept

Back in September, at the 2009 Frankfurt Auto Show, Volkswagen displayed its L1 Concept vehicle, claiming an astounding fuel economy of 170 mpg.  How did they do it?  Well, they start off with an ultra-efficient hybrid powertrain comprised of a 0.8-liter turbodiesel (TDI, which I discussed here) and a 10kW electric motor.  (No plug needed here!)  They use an ultra-light-weight body of carbon-fiber and plastic.  And they designed it with an incredible drag coefficient (Cd) of 0.195.  Improving on the aero efficiency (a topic I discussed here), is a small frontal area, accomplished by arranging the two occupants of the L1 in tandem.  (Remember, the amount of power needed to overcome the air resistance when moving a vehicle is directly proportional to the frontal area, just as it is to the Cd.)

Nissan Land Glider Concept

Nissan Land Glider Concept

At the Tokyo Motor Show a little over a month ago, Nissan unveiled its Land Glider concept.  Unlike VW’s L1, the Land Glider is a pure electric vehicle, with two motors powering the rear wheels.  (No word on the energy efficiency of the vehicle.)  It also has novel technology, such as the handling-improving capability of leaning in the corners, and crash-avoidance sensors to maneuver the vehicle around objects with which it would otherwise collide.  The Land Glider also (presumably) is aerodynamically efficient – at least it looks that way.  And like the L1, this is achieved partly through the use of tandem seating.

Could this be the shape of things to come? Two-passenger vehicles have existed for a while, from sporty roadsters (like the Miata) to econo-boxes (like the Smart).  So, why not cut the frontal area down, and place the passengers fore and aft?  Is this just too impractical – or too unusual – for the average consumer to handle?  With many pushing for purpose-driven vehicles (rather than cars that can do everything, like what most of us drive today), we may eventually see a lot more variety in the types cars on the market.  It’s not so far-fetched that we may see a derivative of the L1 or Land Glider for sale in a few years.  And although tandem seating doesn’t really lend itself to a romantic time at the drive-in, it certainly can play a part at improving the fuel-economy once the wheels are in motion.

Plastic

November 11th, 2009 Comments off

I hate plastic.  Mostly because it, mysteriously, doesn’t dry in the dishwasher.  But also because a lot of things that used to be made with more durable materials (and that are now made with plastic) don’t last very long.

On the other hand, plastics have been beneficial in many respects, especially in the auto industry.  I remember people complaining a few decades ago when polyurethane and polypropylene fascias replaced the large chrome bumpers that were on most cars, but the truth is the use of these plastics allowed for better aerodynamics, sleeker designs, and even improved safety.

ZF Carbon Fiber Reinforced Polymer Strut

ZF Carbon Fiber Reinforced Polymer Strut

ZF Transverse Leaf Spring Axle

ZF Transverse Leaf Spring Axle

The latest issue of Automotive Engineering International describes how plastics are taking the next step in automotive design: being incorporated into suspension components and other structural areas of the car.  For example, ZF is developing a transverse-leaf-spring rear axle utilizing glass-reinforced plastic for the spring itself, as well an upside-down carbon fiber-reinforced polymer strut and plastic spring for the front suspension.  In addition to the benefits of lighter weight (and lighter unsprung weight, which magnifies the handling benefit) the strut can be manufactured with an integrated signal fiber that acts as a strain gauge, providing a warning of any impending structural failure.  (This is not to suggest the chance of a structural failure with these components is any greater than with traditional steel suspension parts.  Formula 1 and Le Mans Prototype race cars have been using composite suspension components for years.  And in fact, these  components may actually be safer, since they won’t rust when exposed to road salt and water, and they can actually let you know when there’s a problem!)

Additionally Bayer MaterialScience is developing polycarbonate windows for use in road-going vehicles.  This again is a case where technology that has long been used in motorsports is making its way to the masses.  The problem with polycarbonate windows has historically been the ease with which they scratch.  That’s not a big deal in racing, where the windshield gets replaced frequently.  But Bayer has developed coatings which make polycarbonate windows stand up to the rigors of life on our nation’s highways.  Here, too, we have the benefits of reduced weight (especially up high in the vehicle, where it affects handling) and increased safety (no shattered glass).

The use of plastics and composites will play a significant role in the design and manufacture of lighter, more fuel-efficient vehicles. (What’s next, plastic engines?!)  …Given how far we’ve come with plastics, it seems that by now someone would have made a plastic child’s sippy-cup that would emerge dry from the dishwasher…

Technical Minutiae

November 9th, 2009 Comments off

When it comes to cars, I’m fascinated with technical minutiae.

In the tech Q&A section of one of the car magazines I read, the question was recently posed, “Are there any disadvantages to direct-injected engines?”  Many automakers are switching from port-injection to direct-injection in an effort to increase performance and fuel-efficiency.  (What’s the difference?  In traditional port-injected engines, fuel is squirted into the incoming stream of air before it goes past the intake valve into the combustion chamber where it is ignited.  Direct-injection, on the other hand, involves injecting the fuel directly into the combustion chamber – and air is the only thing that enters via the intake port.)  Direct-injection is used in many high-end and mainstream vehicles now, and will probably make its way further down-market very soon.

MicroscopeTurns out, there are a couple of concerns with direct-injection that aren’t immediately obvious.  One involves the intake valve itself.  Along with the air that flows past it is the small amount of gases that leak past the piston-rings and into the crankcase, returned into the intake stream via the PCV (positive crankcase ventilation) valve. This is essentially the “oily” air that resides in the bottom half of the engine.  Over time, the PCV system could cause oil-residue to build up on the back-side of the intake valve.  In an older port-injected engine, the gasoline washes this residue away, but in a direct-injected engine, this residue never gets cleaned off.  (Ford solved this problem by adding an additional filter to the PCV system.)  Another concern is that directly injecting gasoline into the cylinder could wash the oil-film from the cylinder walls, increasing wear of the rings.  My guess is that this will turn out to be a non-issue, given the amount of testing that goes into proving the fundamental combustion processes of engine technology.  But this is what I find fascinating – there are significant repercussions to even slight design modifications.

It’s sort of the law of unintended consequences.  (Increased ethanol production caused a spike in the price of tortillas, anyone?)  Not long ago, I had a conversation with an automotive engineer that was studying the role that lubricants (i.e., your motor oil) play in auto emissions – a role that is increasing as vehicles become more fuel-efficient.  Motor oil formulations have been (and will continue to be) altered in order to reduce their contribution to tailpipe emissions.  As an example, the amount of zinc dialkyl-dithio-phosphate (ZDDP) was recently reduced in engine oils, due to its detrimental effects on emissions equipment (such as catalytic converters) over time.  Unfortunately, it’s the ZDDP that helped to protect the metal-to-metal impact surfaces in engine valve-trains up until the 1990s.  Owners of cars built before then are now experiencing increased camshaft and lifter wear, upsetting a lot of folks who drive classic (and near-classic) cars. …A slight change somewhere results in unforeseen consequences somewhere else…

At this point, if you’re still reading, your eyes have probably glazed over.  Technical minutiae isn’t for everyone.  But sometimes, it’s the tiniest of details that matter.

An EcoBoost Ego Boost

October 13th, 2009 Comments off

If you keep up with what’s happening on the auto-scene, you’ve no doubt heard of Ford‘s EcoBoost effort by now.  EcoBoost is essentially Ford’s moniker for adding forced induction (i.e., turbochargers) to high-compression engines to produce power equivalent to that of a V8 (or a V6) with fuel economy comparable to a V6 (or a 4-cylinder).  Automakers have been doing this for a number of years now, but Ford is making it a core part of their strategy to boost their brands’ fuel economy, spreading the technology through virtually all of their models.

2010 Lincoln MKS

2010 Lincoln MKS

I just finished watching the 6 vs 8 – Showdown at Loveland Pass episode of Speed Test Drive on Speed Channel, in which the Lincoln (Ford’s luxury brand) MKS (with a twin-turbo EcoBoost 3.5L V6 making 355 hp and 350 lb-ft of torque) was pitted against a Mercedes E550 (with a 382 hp 5.5L V8), BMW 550i (360 hp 4.6L V8), Maserati Quattroporte (400 hp, 4.3L V8), and Jaguar XF (385 hp, 5.0L V8).  The challenge was to see if the 6-cylinder Lincoln could keep up with the V8-powered European luxury/performance brands in a 3.7-mile hill climb up Loveland Pass in Colorado, with the finish-line nearly 12,000 feet above sea-level.  Expert rally / hill-climb champion racer Rod Millen was given the honor of piloting each of the vehicles.

The result?  The Lincoln came in second, with a time of 172.7 seconds – a couple of seconds (and about 0.8 mph) slower than the BMW, and several seconds ahead of the Mercedes, Jaguar, and Maserati that came in 3rd, 4th, and 5th respectively.  More striking is the fact that the Lincoln actually reached the highest top-speed on the course (109 mph), demonstrating that it was the handling, not the engine, that caused it to fall just short of the BMW’s pace.

I’ve never driven Loveland Pass.  I have driven over Independence Pass – 100 feet higher than Loveland Pass – and realize what a challenge this test actually is.  I also know how anemic normally-aspirated cars can be at extreme elevations – a fact that certainly played to the boosted Lincoln’s strengths.  And if you’re wondering why the car with the least power appears to be the fastest, note that it’s not the peak horsepower that matters – it’s the area under the torque curve, and the Lincoln’s is wide and flat.

I’m impressed.  That the Lincoln can run with, and even outshine, Europe’s best in any test has got to be an ego-boost for Ford.  But I’m even more impressed with Ford’s efforts to bring the technology to all of their vehicles.  The EcoBoost engine in the new Ford Flex (reviewed here by Autoblog) makes nearly 100 hp more than the normally aspirated V6 Flex, with the same fuel economy.  (I’d like to see them replace that old Duratec V6 with an EcoBoost 4-cylinder.)  The same engine is used in the high-performance Taurus SHO.  And there are even plans to use a version of it in Ford’s light-duty trucks.

I grew up in a Chevy family.  (Growing up the rural south in the ’70s, you were either a Chevy family, a Ford family, or a Chrysler family.)  And though my preferences have shifted to a few German marques, I’ve got to give Ford credit.  While the other American manufacturers have gone through bankruptcy and major reorgs in the last year, Ford has not only managed to survive, but they’ve introduced interesting new technology, all while manufacturing some of the better hybrids on the market.  And that, more than anything, should boost their ego.

ecoboost logo

The Hangover

October 1st, 2009 Comments off

I heard a story on NPR today about what auto dealers are calling the Cash For Clunkers Hangover.  September, it seems, was a dismal month for auto sales, primarily due to the fact that so many cars were sold in late July and August due to the CARS program.  The two reasons cited are that people purchased new vehicles earlier than they otherwise would have to take advantage of the incentives, and dealer inventory was quite sparse in the post-CARS weeks.

Is this really a story, though? I wrote about CARS prior to the program here, and midway through it here, and stated that CARS had such an explosive effect due to pent-up demand (i.e., people delayed their vehicle purchase due to the economic downturn).  CARS was intended to counteract this delay by accelerating vehicle purchases – essentially compressing time for the auto industry.  Unfortunately, the program was a victim of its own success and was thus short-lived.  So, is it any wonder that sales slacked off after the incentives ran out?  Not to criticize NPR (one of my favorite news sources), but isn’t this story akin to headlines like “Fans Celebrate After Team Victory?”

CARS HangoverOne good point that was made in the story, though, was that perhaps the incentives were too high, and thus too large a market distortion.  Maybe if the incentives had been only $1000 or $2000, instead of typically $3500 or $4500, auto sales would have been stimulated for a longer duration (though to a lesser degree).  …Then maybe the hangover wouldn’t have been so bad for the dealers.

Perspective

September 2nd, 2009 Comments off

I’m a car guy, and an environmentalist.  I made that clear in my inaugural post.  I’m proof that these two perspectives aren’t mutually exclusive.

In The Road Ahead column in the October issue of Road & Track, editor-in-chief Matt DeLorenzo likens the freedom and spirit of the American cowboy to the mobility now afforded us by modern cars.  (It’s a reasonable analogy, given that the feature article is about the Ford Mustang, Chevrolet Camaro, and Dodge Challenger – 3 American “pony” cars that have recently been resurrected.)  He also makes the very correct point that “the automobile has a social cost – clean air, use of resources, accidents … [that] must be weighed against the benefits – mobility, freedom and independence.”  (OK, “freedom and independence” may be a bit of a stretch, but you get the point…)

Unfortunately, DeLorenzo goes further, and says “there are those who can’t abide these freedoms … [and] would rather see the American cowboy unhorsed.”  He suspects that the push for cleaning up the environment and improving fuel economy is “cover for a larger agenda” to force people to stop using automobiles.  He views this point of view as largely coming from “sophisticates (usually from big cities or across the ocean)” who view our constitutional rights as “merely incidental.”  He effectively equates reducing the environmental impact of our transportation to the demise of one of the great patriotic symbols of America.  (We won’t get into what the great American cowboy did to the Native Americans here…)

…Really?  Does DeLorenzo really belive that there are folks that want to prevent other folks from driving simply because of a desire to suppress others’ rights?  (OK, I’m sure there are one or two such people out there, but they probably also believe that the Apollo moon landings were faked.)  While the “sophisticates” who live in large metropolitan areas might be more likely to place high importance upon improving fuel economy and finding other modes of transport, it’s because the social cost (as DeLorenzo correctly described it) of millions of inefficient automobiles is much higher for them than it is for Johnny Tumbleweed piloting his Mustang across Wyoming – at least insofar as the noise, congestion, and pollution that result.  (Greenhouse gases, on the other hand, will affect Mr. Tumbleweed just as much as they will Winston Urbandweller.)

It’s valid to argue what the real social cost of our automobile use is.  But to suggest that it’s all a ploy to get people to stop driving, while hinting that the effort destroys a piece of American heritage, is ridiculous.  I’m offended – as a car-guy, and as an environmentalist.

cowboy

Rudolf’s Invention

August 20th, 2009 Comments off

In 1892, Rudolf Diesel invented the compression-ignition (i.e., diesel) engine.  The big difference between diesel engines and gasoline engines is that gasoline engines are typically of the spark-ignition type, relying on a spark-plug to ignite the air/fuel mixture, whereas compression-ignition simply relies on physics to cause the air/fuel mixture to ignite when it is compressed to around 5% of its original volume.

VW Jetta TDI Sportwagen

VW Jetta TDI Sportwagen

Diesel engines are significantly more efficient than their gasoline-powered counterparts, and have enjoyed more popularity in most parts of the world.  Unfortunately, the U.S. is not one of those parts.  Although a few manufacturers have offered diesel engines in their light-duty vehicles in the past, about the only mass-market diesel vehicles you can find in the U.S. today are powered by Volkswagen’s TDI technology.  It seems other manufacturers would follow VW’s lead, given the sustained success of the TDI engines.

What’s the problem here?  Maybe it’s marketing: American consumers still remember the horrible diesel engines of a few decades ago, and think of them as noisy, polluting, and slow, when in fact modern diesel engines are quiet, clean, and powerful.  Maybe it’s cost – diesels generally cost a tad more than their gasoline counterparts; however, diesel engines are usually built “tougher” to withstand higher compression ratios, and frequently have greater lifetimes as a result.  And then there’s the efficiency benefits.

…In a past season of Top Gear, the hosts had a contest to see who could drive from Basel, Switzerland, to Blackpool in the UK, driving any car of their choice, but using only one tank of fuel.  Jeremy Clarkson figured it couldn’t be done, so he chose a car that would actually be enjoyable: a Jaguar XJ6 TDVI (diesel) with a fuel economy rating of 35 mpg, and a theoretical range of 655 miles.  James May chose a Subaru Legacy diesel with a rating of 50 mpg, and a theoretical range of 706 miles.  Richard Hammond chose a VW Polo Bluemotion with a 3-cylinder 1.4L engine that gets 74 mpg, but equiped with only a 10-gallon tank.  Before setting off, they properly adjusted their tire pressures, and (in the ultimate display of hypermiling) even sealed the body-seams with tape!

The result?  Richard arrived first, followed by Jeremy, who drove like a bat out of hell with the A/C and all accessories on to demonstrate that it couldn’t be done – proving himself wrong in the process.  …Captain Slow didn’t quite make it.  But, it was an excellent demonstration of the efficiency of diesel vehicles.  Unfortunately, none of these cars are available in the United States.  What will it take to change this?

MORE Cash for Clunkers

August 4th, 2009 Comments off

CARSA couple of weeks ago, I talked about the Federal Car Allowance Rebate System (CARS) program, and the effects it might have on the auto industry and the environment.  It turns out, the program has worked a little too well, at least in some respects.  Nearly as soon as the final rules were published, the $1-billion allocated to the program was exhausted.  Now, the House has authorized an additional $2-billion, though the Senate must do likewise for the program to continue.  The debate is now whether or not to spend this extra cash before fully understanding the effect that the program is having.

Obviously, it seems the program was underfunded.  If we assume the average rebate is $4,000 (which is likely not accurate, but it’s the average of the two possible rebate amounts of $3,500 and $4,500, and the math is easy), then the initial $1-billion represents 250,000 trade-ins and new car sales.  That’s only about 1.7% of the yearly new car sales in the U.S. (prior to the meltdown of the auto-industry).  So the fact that $1-billion was burned through so quickly isn’t surprising.  I tend to think the downturn that we had seen in new car sales wasn’t so much a result of people deciding not to buy cars, but rather deciding to delay their car purchases.  With so much pent-up demand, it’s no wonder the CARS program had such an explosive effect.

The program has certainly had an impact on the auto industry.  Today’s Wall Street Journal (Clunker Plan Gives Car Sales a Lift) describes auto makers’ plans to begin increasing production as a result of the boost in sales.  It also mentions that suppliers to the auto industry plan to benefit as well – ripple effects that result in tangible benefits to the economy.

The environmental impact is less clear.  The US Department of Transportation reports that the average fuel economy of new cars being sold under this program is 25.4 mpg, compared to 15.8 mpg for the vehicles being traded in – a 9.6 mpg average improvement.  Assuming these cars are driven an average of 15,000 miles per year (and assuming my previous statement of 250,000 cars is correct), that’s 390-million gallons of gas saved, or over 3.4-million metric tons of CO2 avoided, at a cost of $290 per ton – expensive carbon mitigation by any measure.

…Of course, to quantify the actual effect, one would have to know the baseline – what would have happened in the absence of the program.  (It’s likely that, since traded-in cars were probably bought when gas prices were lower than they are today, their average fuel economy would still be worse than the new cars replacing them.)  Plus, my calculations are so full of my assumptions as to render them pointless.  But, it makes for good blog discussion!

I Have Two Clunkers

July 21st, 2009 Comments off

Most everyone who cares about cars has heard of the Cash for Clunkers program by now.  Basically, if you trade in your clunker for a more fuel-efficient vehicle, you get an instant credit of either $3,500 or $4,500, depending on the type and mileage of the traded-in vehicle and the vehicle being purchased or leased (with  various restrictions).  This program is intended to have the dual benefits of accelerating the transition of our nation’s light-duty vehicle fleet to a more fuel-efficient one, as well as helping to stimulate an auto industry that’s currently in dire straits.  (Plus, folks buying a new car can get a substantial discount – not bad, politically!)

But, what constitutes a clunker?  Essentially, it’s a car that you’ve driven for at least a year, and that has a combined city/highway fuel economy rating of 18 mpg or less.  Also, it has to be newer than 25 years old.  This means my wife’s Buick Enclave, which we bought new in 2007, and which has a combined rating of 18 mpg, qualifies.  My truck, which on its last tank averaged 12.4 mpg, and which doesn’t have an official fuel economy rating, qualifies as a “Category 3” work truck.  We could trade both these vehicles in today and take advantage of the program.

Crushed CarsThis got me thinking – I wonder how effective the Car Allowance Rebate System (CARS) will have been once it concludes on November 1 (unless funds run out first).  The goal of stimulating the auto industry will almost certainly be reached.  It’s the other goal that worries me.  Who will take advantage of the program?  If consumers who had already planned to purchase a new vehicle are swayed towards a more fuel-efficient choice because of CARS, then that would be wonderful.  On the other hand, if folks are tempted to trade-in a nearly-new vehicle, or one that doesn’t get driven very often, simply to get their slice of the government pie, then the overall benefit could be negative.  After all, the program mandates that traded-in vehicles be shredded or crushed (and hopefully recycled) so that they aren’t resold as used vehicles.  And using my truck – which I probably drove less than 3000 miles in the past year – as an example, the net environmental impact of building a new vehicle (and scrapping the old) is likely negative when that vehicle is rarely used.

I hope the CARS program proves to be an effective mechanism for reaching both goals.  But as for me – I’m keeping my two clunkers.

Lose Some Weight, Will Ya?

July 15th, 2009 Comments off

An article in the current issue of SAE‘s Automotive Engineering International (“Everything but the Engine”) discusses the effect that components other than the engine have on vehicle fuel efficiency.  Among the items discussed are transmissions and the benefits of DCTs (which I previously talked about here) and tire rolling resistance (which I previously talked about here).  (…Wow, I’m very timely, aren’t I?)  Other efficiency mechanisms discussed are reducing vehicle size, using advanced lightweight materials, improving aerodynamics, and reducing the weight of all the accessories that are packed into what have essentially become condominiums on wheels.

Buick Enclave Rear Suspension

Buick Enclave Rear Suspension

Let’s talk about weight.  Our cars need to go on a diet.  I remember last year reading a Road & Track article about the new BMW 1-series (finally, a small BMW to replace the formerly-small 3-series!), and my jaw hit the floor when I saw how much it weighs – 3373 lbs for a manual 135i?!  This is small car?  …At the other extreme, my wife’s Buick Enclave has a curb-weight just shy of 5000 lbs, despite the use of aluminum in some of the body panels and suspension components.  (The Enclave’s aluminum rear control arms are a thing of beauty, though.  GM did do a few things right.  …Am I the only one for whom control arm material is a criteria for purchasing a vehicle?)

More extensive use of light-weight materials such as aluminum, magnesium, high-strength steel, and carbon fiber can reduce weight, but it seems like automakers are more focused on making cars more bloated while using these materials to offset a portion of the weight-gain that would otherwise occur.  (They add 100 lbs of features, but only 75 lbs of weight!)  On the other hand, my race car weighs a scant 2500 lbs, and that’s with an old-school steel tub, a heavy steel cage, and 70 lbs of ballast in the floorboard.  And in its day it would carry 2 adults and 2 children (sans cage) plus their luggage.  Granted, it lacks all the amenities that consumers demand today.

Lightweighting is a good thing, with compounding benefits.  Reducing the weight of the vehicle means a reduction in the size of the engine needed to move it around, smaller brakes to stop it, and lighter suspension components with which to control it, all of which lead to further reduced weight!  At the same time, handling is improved and stopping distances are reduced.  So, why haven’t we seen this in our cars?  One answer is that many of the advanced materials are still too expensive to be cost-effective.  Secondly, consumers demand more and more comforts such as DVD players, Ipod adaptors, Bluetooth connectivity, Big Gulp holders, and hip room.  Finally, some argue that smaller and lighter-weight vehicles are less safe, backing it up with statistics showing increased fatalities for occupants of such vehicles.  And while it is true that today’s small vehicles won’t fare as well in a crash with a Ford Excursion as the Excursion will, this does not take into account the effect that smarter design and the use of advanced materials have on occupant safety.  Cars aren’t like billiard balls – there are many more dynamic forces at play, and heavier doesn’t necessarily mean safer.

Automakers need to build small, lightweight cars – not small versions of what they already build.