I don't know the percentage of differences in fuel economy between gas and diesel but we all know there is a difference and diesel wins. Diesel wins in power too when involving tractors. Even A V12 diesel is being used in racing that is blowing away the competition. When comparing equally matched horsepower ratings of engines diesels win in torque every time.
Example. HP=torque x rpm/5252. Torque=hp/(rpm/5252).
A 22hp gasser that gets peak hp at 3600 rpm has 32 ft/lbs of torque. A 22 hp diesel that is rated at 3200 rpm has 36 ft/lbs of torque. Yes, a very small differance but still a differance. Play with the numbers when using higher and lower hp ratings and you'll see where the advantages of diesels really shine in torque. The formula used is the same formula dynomometers use to calculate hp from torque measured. The rpm's used are from Kohler, Briggs n Straton engines and kubota diesels.
Yes older diesels can be a little bit uncooperative in extremely cold weather, but that can be over come with a little upgrading and preperation. Ever had a choke problem on an old gasser? How 'bout a float stick? How 'bout a bad temp sensor on a fuel injected engine? Map sensor? MAF sensor? Coked throttle body? Bad PCV valve? Vacuum leak?
I know gas engines can be reliable if maintained properly but that's the point. When these things go bad it's when you need them most. I know, I fix'em for a livin'. Diesel engines are just plain reliable. I don't have to fix very many diesels. 99.9% of what I fix is powered by gasoline and it's not 'cause my customers don't have diesels either.
Since a diesel engine spins at rpm's that are much lower than a gasoline engine it will last that much longer. Can you get 300,000 miles out of a gasser. Sure, but how many tune ups are required. How much more fuel did it use. If I had to do it over again my truck would be a diesel. I wish my Prius was.
Yes diesel parts are more expensive. A diesel engine is the same to rebuild as a gas. The parts are just a bit heavier. Other than initial cost and having to bleed the fuel system if you run out of fuel I can't think of a single reason why a modern gas powered engine would be better than a diesel.
Time for a peanut butter and jelly sandwich

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