I have owned 4 XJs and 3 ZJs with the 242. I have found that 2wd is good for 2 to 4 MPG (Imperial) on the highway. My present DD is a 98 XJ 4.0 auto with a 242. It will easily get 26 mpg in 2wd on the highway locked on cruise at 110 kph. In FT4wd the best it will do is 22. We have owned this Jeep since new and it now has 185,000+ kms on it. The figures are hand calculated. I owned a '98 ZJ Laredo into which I transplanted a 5.9 Limited drivetrain with a 242. On the highway it would get 16 to 18 mpg in 2wd. In FT4wd on the highway it got 12 to 14 mpg.
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