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We're slowly starting to see more diesel passenger-cars offered in the U.S., mostly from German companies. I have driven several of the newer diesels, and the refinement, power and economy is very impressive. I would venture to say if more people would give diesels a chance, they'd buy one.

For a while, it looked like we were going to have a bunch of diesel cars on the market from Nissan, Subaru, Honda, Acura and others, but lately, it seems a lot of these companies have gotten cold feet on their diesel plans for the U.S. What, if anything, do you think would really get diesel car sales in the U.S. to really take off? Do you think the high price of diesel relative to unleaded a factor?  

I don't think diesel will ever be as popular here as it is in Europe. The mandate for ULSD fuel made the price of diesel spike at the same time increasingly difficult emissions regulations made diesel vehicles less fuel efficient.

Look for the U.S. market to have, maybe, 15 percent of the fleet powered by diesel. That number will probably be higher for trucks and SUVs with optional diesel engines and lower for any passenger cars that might have a diesel engine option.

Diesel doesn't make sense for everyone, but it gives you the option for respectable performance and quite good fuel economy at the same time. Too bad the price advantage is all but gone unless you drive A LOT of highway miles each year.  

Phil, even 15 percent would be pretty significant market penetration for the U.S. I just wish we had more options when it came to diesel cars. Right now, it's basically VW, BMW and Mercedes, and soon...Audi.  

Having more options opens up a whole can of worms with building a business case. Diesel engines are expensive to produce and now we can get a lot of the same technology in a gasoline engine (think direct injection and turbos) which can produce amazing power from a small displacement engine. That can improve fuel economy and you're burning cheaper fuel. Aside from the fact the gas engines will be lighter than diesels and there is a lot more R&D money for regular gas engines.

I don't disagree 15 percent is significant, but we'll never see 50 percent like Europe. It just doesn't make sense here right now.  

I was actually talking to a friend of mine the other day about this, and I think the market segment you're going to see the biggest inroads for diesels in the U.S. are light trucks and SUVs. Mainly because of government pressure for fuel economy. But the buyers of those vehicles don't want to give up power & capability. Diesel is just about the only way to maintain both.

Even with GM's 2-mode hybrids, they take about a 50% haircut in towing capacity compared to an equivalent conventional model.

Personally, I really want to see more diesels in passenger cars, but it looks like economics and consumer preferences will dictate you'll seen them first in trucks & SUVs.  

I don't think the 2-mode trucks take a huge hit in towing capacity. Ive towed with one and it makes for a MUCH better tow vehicle than a traditional truck. They may not match the 10,000+ maximum tow capacity of the most capable Silverado, but trust me nobody needs to tow 10k with a 1/2 ton truck. The 2wd trucks will tow 6100 lbs and that's not too bad. It would be nice to see a 7000 lb rating, but I don't think it's a huge problem to be at 6100 lbs.

Check the fuel economy on a new heavy duty diesel truck. It's not nearly as good as the trucks of the late 1990s and early 2000s. The new emissions regs really kill the fuel economy advantage of the big diesel trucks. Cleaning out the particulate trap (which happens a lot more often during towing) burns a lot of fuel that doesn't get the truck any further down the road. I did about 1300 miles in a diesel F-250 last summer towing a trailer and the fuel economy was not what I expected.

Diesel still makes more sense than a big block gas engine, but the fuel economy has taken a huge hit in the past few years.

I want to see how the EcoBoost F-150 performs. That could answer the economy/cost problem. Don't look for any diesel 1/2 ton trucks, they've all been put on hold for the foreseeable future.  

The only half-ton truck I've heard of that still has a good chance of making it to the market in 2010-2011 is the Duramax 4500.

I think within the next couple of years, once we see the development of more sophisticated after-treatment systems for diesels, you'll see fuel economy improve. The irony of the current-generation diesel emissions-control devices is they increase fuel consumption. The irony has not been lost on the diesel enthusiast community.

The figures I've heard for the Dmax 4500 are 18-19 city, 24-25 highway. Those are outstanding figures, even relative to the hybrids.  

I think Phil's right - diesels will never have a sizable market penetration because modern gas engines pretty much eliminate all the advantages diesels had.

I can't wait until Ford applies EcoBoost to its 4-bangers.  Woohoo!  

I wouldn't say modern gas engines "eliminate" diesel's advantage, but the advantage is much slimmer than it used to be. Direct-injection and turbocharging on gasoline engines give many of the advantages of diesel, with only slightly poorer fuel economy.

Don't get me wrong, I'm as excited as anyone about the new EcoBoost engines, but I'm not buying the premise that they're a "replacement" for diesels.  

while diesel fuel is 50% more than gasoline, there will be a very small market for diesels.  

When gas prices soared, the cost of diesel maintained the same gap (vs. same percentage) over gas.  If it gets up to the point where diesel costs only 25% over gas, maybe we'll see more.

The manufacturers didn't get cold feet.  They saw their business cases evaporate and wisely pulled back before disaster struck.  

Diesels made more sense when diesel fuel was cheaper than gas. Now I think hybrids will be the trend, especially as the technology becomes more and more efficient.

So I'm not sure why the German automakers are rushing diesels to North America (VW Touareg, BMW 335d and X5, Mercedes, etc.).

VW's four-cylinder TDI will do well. It has an established following and has developed a reputation for its diesels over the decades.  

Three things supress diesel car sales in the US (trucks are a different topic):

-  Diesel fuel cost v. gas.
-  MPG hit from advanced emissions scrubbing in new diesels.
-  Only performance diesels are available.

Fuel cost:  The spread between gas and diesel is temporary and somewhat artificial.  It's based on refinery capacity and demand, so it *can change* - it can be managed one way or the other.  (For example, national diesel price is only at 11% to gas, already a significant per mile advantage to diesel).  The gap has slowly, steadily, been shrinking.

Scrubbing Hit:  We're only seeing the 1st gen of truly clean diesels.  The tech will advance and get the efficiency and cost back down, driven by euro markets.  (Remember the tech disruption, panic and cost cries for the first catalytic converters?)

Performance diesels: we *only* get the top shelf perf diesels here in the US.  The majority of the euro diesels are the little 4 bangers.  Under the "Americans want power" market penetration plans developed years ago, VW, MB, Honda, Subaru, etc. are stuck spec'ing perf diesels, which reduces the impact of diesel economy and efficiency.

What's missing is that diesels are more efficient than gassers by about 30%, if the issues are managed - and I believe they can be - diesels exceed hybrid efficiencies (~20% above straight gassers), with simpler technology/machinery and cheaper-to-refine fuel.  Current euro-diesels also put out the same or lower carbon emissions as gas hybrids.

Boston Consulting Group recently did the following study that places diesels and hybrids in about the same region in terms of future cost, emissions and efficiency.  http://www.bcg.com/impact_expertise/publications/publication_list.jsp?pubID=2817

The chart on page 4 (Exhibit 2)is particularly interesting.

Primarily, diesel cars can be competitive here if some of the small "economy" diesels are offered.  This will be aided by diesel demand/supply levelling out (like any market, lower-cost-to-produce product should decline in price) and the continuous development of better/cheaper emissions control.

But, diesels are late to a game with a petroleum game clock ticking away.  Hybrids took 10 years to get a modicum of market acceptance, so overall market share may only get to high single digit %, before the petro clock runs out.  BCG makes some estimates for 2020 that are probably as good as any for the US - 74% gas/18% hybrid elec/7% advanced diesel.  
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Graduate, Rodan School of Automotive Design

I agree diesels are fighting an uphill battle in the U.S. from both a perception and regulatory standpoint. Hybrids are definitely winning the PR war with consumers and politicians and government regulators.

Even with all the emissions after-treatment stuff, it seems to me diesels are a more elegant solution to fuel consumption than hybrids, which from an engineering standpoint are very complex.

While I rarely give GM major kudos, I actually think Voltec (or E-Flex or whatever you want to call it) makes the most sense, in the interim period. Just use the gas engine as a generator, and suddenly, you remove a huge component of complication from the drivetrain standpoint, rather than trying to integrate gas and electric propulsion.

I'd love to have a pure plug-in electric that can go 300 miles on a charge and only takes 5 minutes to charge, and doesn't cost six-figures. I'd gladly give up my ICE if one existed that didn't cost an arm & a leg. But I don't think we're going to see such a vehicle for at least another 5 years.  

Well, diesel is down to $2.13 national avg.(v. $1.91 gas), a 10% premium, that is below the diesel's 30% advantage.  Breakeven is around $2.48 for diesel at $1.91 gas.  If price can stay in this range, and buyers can understand per mile cost vs. per gallon cost, diesel sales can get going.

You're right about the engineering complexity - 2 engines cost more to design, build and support.  GM's ER solution is a lot better, but the quantity of batteries is still the issue, even if you're only getting 40 miles range v. the ~300 mile range needed for full EV.  The Volt's battery is about 10X the size of the Prius' and an EV's will need to be that much bigger to achieve decent range.  

Current Prius and Ford parallel hybrids have batteries that are only 1600 watts - only 3X bigger than your standard car's.  

Diesel can make a good case as a 'transition' fuel to the next gen (cheaper) PHEVs and EVs, but the government only seems to plan in narrow 'absolutes'.  In this case, CARB's outdated mantra of the '90s, "No diesels for you!" still echoes in the halls of government.

I might need a good highway car soon; decision would be among C30 (good high rig; middling mpg), Jetta TDI (perfect design for need, but reliab Q's, boring looking),  Cooper S (excellent mpg, good style, too frenetic for hwy?), and the Gillette Fusion Hy (perfect design for need, but a bit 'spensive, and ugly - it has that US Ford front end).

The perfect car highway bombing work car for me would be the Volvo C30 with unobtainable D5...  
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Graduate, Rodan School of Automotive Design

Diesel price is projected to drop below gasoline by April.

While it reflects the drop in demand and may not hold, it is cheaper to produce and additional capacity (refineries) are coming on line in 2010.  If demand remains low and capacity is introduced, the 'traditional' price relationship of diesel to gasoline may return.

Today, we're at $1.93 gas/$2.09 diesel, national average.  That puts a tidy VW TDI "performance diesel" equal to the per-mile cost of econo kitted, scrotum-shrinking hybrids.  

If this price relationship stabilizes people may discover that you get more car, much better performance and the same emissions as the hybrids.  (...isn't that what the europeans have been saying all along?)  
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Graduate, Rodan School of Automotive Design