In a new car (like a 2000 ford Ranger), what speed will result in the best gas mileage?
Idle Speed.
This topic has been discussed recently:
Farmer, wouldn’t having the engine running but not having the vehicle moving lead to the worst possible fuel consumption, ie no miles per gallon?
True story: Dad has a Jaguar XKE which actually works roughly decennially. About ten years ago, before the speed limits went up to 65 and above, we found ourselves very low on fuel and running out fast on a patch of I-81 that had little but moonshine to fill the tank.
“Hell with this,” said Dad. He slipped out into the left lane, kicked the Jag up to 80, and cruised all the way to Roanoke before filling up. While frantically dodging 18-wheelers, he explained that the XKE actually ran most efficiently at 70-80 mph, and 55 was the absolute worst speed the car could perform at, as it was too low in fourth gear and too high in third. I tried to counter him with arguments about air resistance and friction, and let me tell you this: don’t argue with a speeding rocket scientist. He won’t listen.
Anyway, this didn’t answer your question at all, but it does allow me to say this:
Happy Birthday, Dad. Hope you didn’t spend it in the garage.
minding the fact that I’m not an expert or anyting…
It has seemed to me that the best gas milage will vary from vehicle to vehichle depeding on it’s weight. You have to find the ‘balance’ of the car’s weight as relative to motion. For example, my '77 Chrysler New Yorker (big, heavy boat) balanced quite micely at about 75 mph. The current '86 Poniac 6000LE balances at about 65 mph. These balance speeds also got me the best gas milage.
This probably souns really strange, but it works for me.