In the UK, similar to France, quite a high percentage of passenger vehicles are powered by diesel engines (Peugot, Ford, VW, Vauxhall). Diesel engines by design have a higher thermal efficiciency, are therefore more fuel efficient. Gas mileage of 40 mpg are absolutely standard. and comfort does not suffer.
Perception in the US re diesel-powered passenger cars is not on the same level as in Europe, although it is acknowledged that companies like VW Audi and Mercedes have very fuel-efficient cars and are competing with technologies such as hybrids.
Here in the US, power and acceleration rules (see all the articles in the car journals; the more the better, is that true???), but where can you use this in 65 mph zones?
There are many different ways to achieve fuel savings. Diesel technology is not the only one.
General Motors is slowly realizing the wealth and depth of resources that was accumulated by their reseach and development centers in Europe. Cubic inches in a combustion engine is not an indication of progress in automobiles. Smart utilization of resources is a longer-term aspect that unfortunately very few customers realize.
Admittedly, old cars (with their accompanying large engines and lower output) have their charm, but nowadays we should think in terms of sustainability and resource utilization. Today, with newer technologies, car companies can achieve the same - if not higher output - with smaller, but smarter combustion engines. None of the perceived "sporty" companies (Porsche, BMW, you name it) have shied away from the "heating oil" burning engines. and I personally can attest that these engines lack NOTHING. I have driven them in Europe.