mine is
year: 94
mileage: 145k
tires: p235s
driving style: on interstate alot speed limit then and in city i use all of my xjs horses
aftermarket: nothing (possibly forced air intake soon)
city highway ratio: 25/75
mpg: 20 highway 14/15 city

 

I was getting 23-24 and in the last few months its went down to 15!!

the motor was surging like crazy so I replaced the fuel pump and both filters.
the surging went away for three days and........ dum dum dum! the surging came back.


the carter "after market" pump also does not make the power the stock pump did.

so I guess I will drop the tank again and do the pressure req and maybe a different pump.

sad

 

I got 25ish mpg coming back from Santa Fe to Denver with a tailwind the whole way. It was great! Still doesn't beat driving the lady's 2.0 Golf. That thing buzzes for so long, I need to pee long before the gas needs a refill. Otherwise I'm a solid 19-20 on the highway. I try to avoid intown trips, since I can ride my bike. Best way to get good mileage is to not drive.

 

On 4.5" lift, 31" Toyo ATs, 165*stat, headers ans 2.5" exhaust, stock gears, and the weight of bumpers and normal tools/trail gear, my '95 auto XJ will pull 20mpg if I baby it and cruise about 55-60mph @1800-2000rpm, but driving like a sane person at 65-70mph @2000-2100rpm I get around 17mpg...but because I like the sound of my Banks headers and 2.5" exhaust, it's closer to 14mpg avg.

Around town sucks, maybe 12mpg because I like the skinny pedal lol.

The key with the 4.0L is to keep it at 210* and under or around 2000rpm