What generation is your Jimny? Odometer reading? And what oils, fluids are you using?
Suzuki claims 38.1mpg (16.2 km/l) for the 2019 660cc turbo JDM Jimny with the R06A, and Top Gear's road testing showed 40 mpg (UK) at best for the 1500cc Europe market model with the K15A, which is 14.16 km/l. Again, these numbers are for the newest Jimnys, with manual transmissions.
I find it hard to believe anyone is getting better mileage with an older Jimny and a 3-speed or 4-speed automatic transmission.