I assume that a lot of you folks realize that the amount of energy in a gallon of gas is LESS than the amount of energy in a gallon of diesel. i.e. "Per gallon, diesel fuel contains about 12% more energy than gasoline, thus when burned in engines of comparable efficiency means that diesel powered vehicles should get about 12% better mileage, which is in the ball park." See this link:
http://www.arewetoast.com/energy-content-of-selected-fuels.htmlSo ... an equivalent state of the art and horsepower gasoline engine BETTER get worse mileage that an equivalent state of the art and horsepower diesel engine in the same vehicle ... or some laws of physics are getting violated somewhere.
Between gasoline and diesel engines of the same horsepower, torque delivered to the drive wheels is all that counts. However, the gasoline engine will have to spin faster (due to less energy per gallon of fuel) to get it's equivalent horsepower converted into the same torque on it's drive wheels as the diesel does spinning at lower RPM. Hence the gasoline engine will need different gearing than the diesel.
I see comments all the time about "how well a diesel engine will pull" over what a gasser will pull (given the same base horsepower). What this probably means is the driver of the diesel likes to not have his engine spinning as fast as he would have to spin a gasoline engine to do the same job.
The fuel industry has of course known this since the beginning of time ... and hence the overall higher average price of diesel per gallon down through the years. Dollars per mile is what counts - not miles per gallon.
That being said, I've noticed that the V10 in our motorhome can be made to hold us right beside diesel motorhomes on mountain grades - but I have to rev it to do it. I've had to get over the nervousness that those high RPMs used to cause! ;)
