I typically get 25 mpg cruising on the hwy up to 70mph with gentle acceleration. I get better results not using cruise control and slowing down to 60-65mph(to maintain lower engine load) on the inclines. FWIW, as a comparison we rented a Merc E220 CDI wagon in Germany and got 980km(609 miles) on one tank or 70 liters(18.5 gals) of diesel fuel... or ~33 miles/gallon. That includes speeds up to 220kph(137mph) on the autobahn. I'm seriously considering a diesel car/SUV to replace my wife's Lexus SUV(v8 gas hound) which gets only 17mph at best if I drive 55-60mph.

 

The same thought crosses my mind several times a day when visiting p-car forums. In fact I was going to ask why my rotors went a funny burnt orange color after I washed my car this weekend, but used the search function and found the answer 12,000 times. Who would have thought so many people had never washed a car before...

 

I did some experimentation with data logging after reading an article talking about how faster acceleration to 60mph is counter-intuitively more fuel efficient than slower acceleration because you get to optimal gearing quicker, and decided to put it to the test. I discovered that, no, dropping the throttle is not more fuel efficient at all; in fact it uses quite a bit more gas, but is still well worth it. Even moderate "there's a cop behind me" acceleration used more gas than pretending I was in a Prius. Then I realized the guy in the test was comparing 0-60 times of 15 to 45 seconds. WTF is up with that? 15 seconds was my slow time; I don't think I could take 45 seconds if I tried.

 

I leave the neighborhood at the same time as a new Telsa. While a very sexy car for design, I could not own one. It does not make any CAR sounds. While the car may get excellent millage, I say MPG be dammed. I need gurgle, snappy acceleration and aural assault.
3.8 liters of therapy, whenever I can.

 

You cannot beat diesel for highway MPG!