Automobile fuel efficiency
Engine braking vs coasting
In my V6 1997 Passat GLX I found over the years that engine braking got me better mileage than idling during braking. When I started driving a 1999 Audi A4 with a smaller, turbo-charged engine, I found that idle sipped so little gas that it often was better to idle than to engine brake in it.
Now that I live in hilly Ithaca, with a 2007 Passat Wagon I have found that the choice of methods of braking depends on the speed and the slope of the hill.
In all these cases, the car has had a manual transmission, and I have used the on-board mileage computer to help with the studies.
Why automakers don't provide North America with their more fuel-efficient models
Automakers claim that Americans don't want the fuel efficient vehicles that people in other parts of the world enjoy. In fact, demand for fuel efficient cars is just not as steady as it needs to be for automakers to be able to plan a release. Model production is planned two to five years in advance, and fickle Americans, on average, only look for fuel efficient models after peaks of gas prices that only last a few months, and those gas price peaks are not predictable in advance of more than 6 months.
I, for one, would pay thousands extra to have a much more efficient version of the car I currently own, and it turns out there is such a model available in Europe. I currently drive a VW Passat Wagon with a 2.0 turbo gasoline engine. While VW has decided to remove the wagon from the North American market, it is expanding its offerings in Europe in the fall of 2012 to include a turbo diesel engine and even all wheel drive, and the two combined. I wrote to VW letting them know I'd love to buy one in the US, and they replied that they look at such inquiries to measure interest. Anyone can tell VW and other makers what they really would like to see in the market by contacting them through their web sites. Here are some sites of companies that offer better cars overseas:
