I won’t try to talk you out of it either.
Diesel is typically 10% not 10 cents more in my drives. For sure, you’ll feel the torque difference. I’ve driven both diesel and gasoline pulling a 4000lb trailer. There really isn’t a comparison. I think your MPG estimates are probably about right. Does that matter? Not if you don’t mind driving slower and feeling even small grades. I survived pulling my 4000 lb trailer with my gasoline engine.
You can improve the effective torque by changing gears, but that just means you’ll turn higher RPMs. That will affect your MPG, for sure. Some people don’t care if they run 5000 rpm in the mountains. I’m not in that camp. If I was to switch to a gasoline engine, I’d also do some power adders, but I don’t know how feasible that is in your part of CA.
I didn’t buy my diesels to save money. The math isn’t a simple problem, and even if you think you have the math right, maybe your situation changes and that throws it off.
One more thing about MPGs posted here ... many here rarely go over 62 and don’t mind going 50 over the mountains. Obviously, their numbers are going to be way off if you drive 70 or more especially with different gears.
