Which car is the most fuel efficient?

I live in France and can give you a really key number that "almost explains everything"
Here in France and several other European countries but not UK, the percentage of diesel cars in national car fleets is around 75 PERCENT
Thats right
What is the percentage diesel cars in the US car fleet ? Check it out.

For starters 1 gallon of diesel fuel contains 10% more energy in it than 1 gallon of gasoline, so there is one straight advantage for diesel cars
You want to really know why European car fleets are now 75% diesel cars ?

Here in France the price of 1 litre of 98 octane gasoline (1 US gallon = 3.785 litres) is around 1 euro 60 cents, that is $ 2 and 32 cents per litre
Now get the price of a US gallon of gas here in Euro: 2.32 X 3.786 USD
You will be impressed !

One the downside for diesel cars they smell, they need etra powerful batteries for starting, they emit a whole lot of microparticles with serious cancer risks - but who cares if they are cheaper than gasoline cars ?

For the Most Fuel Efficient Cars one would have to move to Europe and Japan, as they have more stringent rules than we do here in America.. but here is the US Governments List of the most efficient cars http://www.fueleconomy.gov/feg/topten.jsp

The most fuel efficient car is the one that stays put in my garage! During this time of $4/gallon "regular" and $60 to fill my Honda Accord, our organizational support of telecommuting is appreciated by all. Also we've embraced video conferencing to the degree it has dramatically cut fuel costs and windshield time for all businesses within our organization.

And when I have to drive ... I love my 2009 Honda Accord's (EX-V6) ability to drop in "Eco Mode" and run on 4 cylinders (versus 6) to preserve fuel! Brilliant!

I have a 2009 mini-cooper 6 speed (non-turbo) and get about 45 mpg on the highway... Love the car and the gas mileage...

That would be my 2002 Honda Insight. I have the automatic and have been enjoying 55+ MPG for the last 8 years. It is the most fuel efficient product car ever manufactured. Honda produced them from 1999 - 2006. They are a work of art, reasonably priced, full aluminium construction and no problems what so ever. This is not the same car as the current Honda Insight. The current one is an replacement for it and still does very well, if a brand new car is what you are looking for.

In terms of brand new cars, I like the Hyundai Sonata. The 2011 2.0T is 22 city/33 highway and will go from 0-60 in about 6 seconds. Not too shabby! And I like the looks of it.

I have a 2008 Toyota Prius and have always loved the car for it's excellent "econobility" and drivability. Yes, the Prius is a fun car to drive--and yes, I have owned sports cars and luxury cars--but the Prius has an excellent balance of practicability, functionality, and low cost. The smart key system, integrated bluetooth, GPS and other features make it a great car for getting around, it drives well, carries bikes and skis better than my SUV/van, and after 55,000 miles, the car has had a few oil changes and not a single issue. Fuel economy in the 46-50 MPG range and a moderate cost have made this a very economical, reliable and practical car over the years.

I guess it's not my Honda Pilot :-(. But pretty good for an SUV. I've been thinking about the Chevy Volt but wanted to wait until it really hit the market to see how people liked it.