Congratulations! That's quite impressive for (mostly) 40-year-old technology.
I bet you'll break 21 MPG before long.
A while back, a friend said, "You bought a
Mustang for
fuel economy? Yeah, right!"
She was shocked when I told her what I'd managed to squeeze out of it. (And I'd only gotten into the high 29's at the time.)
My current goal is 32 commuting. Probably won't happen 'til next Spring, though...