I have a 1996 XJS, AJ16 engine, about 113k miles.
I do a mix of city and highway driving. I seem to be averaging 15mpg. While I don’t drive conservatively, I’m also not hammering down the gas pedal at each green light either.
My LTFT is zero. Both banks.
The only unusual reading I’ve picked up is that my coolant never goes about 180. With the heat on its at 176F and without heat, it’s at 179.6F.
Would a stuck open thermostat cause that kind of fuel economy?