Hmm, are those Imperial gallons he's getting 21 mpg with that Diplomat? Cause if so then it works out to about 16 mpg using US gallons.
I had a 72 Swinger with a 225, 2.45 gears, and it was lucky to pull 10 mpg on it in mixed driving. But I attribute that to the 2.45 gears. Swapped in an 8 1/4 to replace the 7 1/4 and never thought to see what gears it had. That was a big mistake.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
