You're probably right about the mpg. The odometer has been broken for ages and I was estimating milage by adding up my commutes. I am at high altitude which does help a bit due to the lower wind resistance however.

6cyl anything from that era is almost always rough on gas haha. My dad also had an XJ -- it's actually what I learned to drive in. But yeah, terrible on gas.

I have a older mower too (not as old as you). But it's creeping up on 10 years old. It's a Troy-Bilt with the Briggs motor. Same though, first start of the season it's sometimes two pulls, and then almost always just a single pull after that.