I beleive it was Road & Track that did a comparison between the Mercedes Benz E250 luxury sedan and the Toyota Prius.
Their conclusion was that the bigger, faster, more powerful, luxury sedan actually was the more efficient sedan between the to in a face-to-face test.
I tend to believe them. It seems that EPA data is skewed in favor of gasoline engines, but in real life diesel engines deliver some amazing performance. My Audi A6 TDI has just under 20,000 miles on the odometer and my long term fuel economy average is 36.6 mpg for that entire 20,000 miles. It goes from 0-to-60 in just over 5 seconds and has full time 4 wheel "quattro" drive so its great in the snow. Diesel is also cheaper than gas in my area. My daughter has a diesel Jetta, her odometer is right about 109,000 and she averages over 37 mpg.
One of the fastest, most responsive Mercedes sedans I ever owned was a 1986 turbo diesel 350 SLD. 190 HP. Not great off the line but as quick as anything once you got it moving. I also owned the same 143 body in three other Benzes, all gasoline 450sel (238 HP) and 560 sel's (328) of similar vintage.
Gas models got 15 to 18 MPG The diesel got 20 city 24 highway on what at that time was the cheapest fuel at the pump. Back in the 90's that was something.
Given the low maintenance costs and reliability of the diesel ( I got over 400K before I sold it) the diesel far outperformed the gas models in overall cost per mile.
Even at todays price for diesel, I prefer it in my larger vehicles. The ones I wish to keep for along while. My 1995 Dodge one ton gets 20MPG on the highway,
loaded. 25 years later some gas model 1/2 tons can do it. Empty.
Diesel is a fuel we can grow cost efficient to pumping Crude. And unlike ethanol, it requires less refining and no modifications to old engines. 50/50 blends of Bio and petroleum runs exactly like straight diesel. And doesn't cost $4.00 a government subsidized gallon to produce. Unlike corn,,,, Beans tend to enrich the soil.
End of rant.
Thanks Melensdad, for setting up the soapbox