I blogged about past and future cars here: http://ourchangingclimate.wordpress.com/2008/10/02/the-car-of-past/

Here’s an example of a ICE car which gets 100 mpg (still in an experimental phase I believe):
http://evolution.loremo.com/content/view/97/196/lang,en/

On a test bench you can get still much better than that, but stop and go and going uphill will start to be difficult: the opel P1 experimental car got >350 mpg. Needless to say, it won’t have the same features as the cars you generally see on the road. But it may show that large improvements over today’s mileage are possible.

Bart

If the question is “will we see such cars in the next five years?” I would have to say “don’t bet on it.”

This is also the issue of small particles (global warming). Diesels emit much more black carbon (soot) per unit distance traveled than gasoline engines.

The IPCC may minimize black carbon as a source of global warming (and also as a source of melting ice in the Arctic), but that doesn’t mean the IPCC is correct:

http://scrippsnews.ucsd.edu/Releases/?releaseID=891

In fact, it has been argued that diesels are greater contributors to global warming than gasoline engines (at least over the first decade after emissions):

http://www.scienceblog.com/cms/diesel_cars_may_promote_more_global_warming_than_gasoline_cars

P.S. Over the next 2-3 decades, black carbon emissions from diesel engines in Europe should decrease dramatically (by as much as 90 percent). Unlike with CO2, any climate impacts (e.g. on Arctic ice melt rates) should be closely timed to the reductions in emissions; there will be no need to wait many decades to see if there is an effect, as with reductions in CO2 emissions.

As pointed out above, 100 mpg is not about cruising efficiency, it’s about starting and stopping losses. A car is far more fuel efficient cruising at 60 mph on the highway than averaging 15-20 mpg in stop and go traffic.

I must admit, I’d prefer a bigger car with less electronics and more leather though

And diesel engines are generally more heavy, as is – as Mark explained – but even more due to the the turbo or compressor. Also more expensive in buying price. But diesel is inherently more efficient by physics (diesel vs otto efficiency) and by energy per liter/gallon. It will make up for that.

The problem with diesel environmentaly seen however is in its small particles (cancer), sulfur (acidification) and NOx (lungs and acidification). You need high grade diesel, and a NOx-kat and small particle filter to get the same cleanness as a modern petrol engine. See e.e. Mercedes E class BlueTec. Sofar California is the only place where these things are mandatory (indirectely by emision regulations). In diesel loving Europe this will in effect only happen when the EU euro 6 regulations kick in. This will up the price of dieselcars …

So CO2 wise diesel is a good thing to look at, but price wise and in terms of other emisions it has its own set of problems. We tend to define environment to much a CO2 today and forget about the rest. Personally I rather have CO2 emmisons in my backyard than any of the other nasty stuff …

No, you will never get 100mpg out of a large car driven in Phoenix at a comfortable temperature. Still less if it is stop start, but even if its being driven at 50 or 60 mph on a highway.

You will get it out of a small, and this means Peugot/Citroen 105 or 205 sized, car, no air conditioning, driven mostly at constant speeds under 50.

If you simultaneously with the takeup of such vehicles reduce the average mileage of them, you can make a big difference to total energy consumption on transport. You have to do both: improve mileage, and also reduce miles driven.

Hybrids are just feelgoodery. They do not in fact, in driving which is typical of what people do, deliver any better mileage than economical non-hybrids. Specifically, smaller conventional cars always deliver better mileage than larger hybrids.

What does this tell you? You really want to reduce gas consumption in the US, restructure the towns and suburbs so people do not have to drive fast and carry lots of shopping. Restructure them around public transport and local services and routes that are safe to walk or bike.

You cannot maintain existing lifestyles of shopping, working and living, and existing layouts of roads houses and communities, and existing modes of transport, and still make large reductions in transport fuel consumption. People are going to have to travel by muscle power for shorter distances, and by public transport for longer ones, and that means restructuring of the physical environment.

Or not doing it.

Diesel engines have higher compression ratios. That means they have to have more muscular connecting rods, crankshafts, and other engine parts. So I’d expect that a diesel of equal displacement to a gasoline engine would be somewhat heavier.

Are European car safety features on par with U.S safety features? If so, I think the weight argument is undercut, if just a bit.

Are diesel engines generally lighter, even with the turbo or compressor?