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99 Jeep Cherokee Gas Mileage

I have a 99 Cherokee and I’d like to know if there is anything that can be done to improve gas mileage. I realize this is not an economy vehicle but I’d like to get the most out of it. It’s a 6 cylinder with auto trans and 125K miles. In the past I have gotten close to 20 mpg highway and anywhere from about 12 to 15 around town. This winter was particularly bad so I changed plugs, wires and dist cap but no real improvement.

I’ve seen online adds for a plug in computer chip or re-program that promises increased power AND increased mileage but that seems hard to believe. Are there any products or modifications that will give legitimate increase in mileage? The car runs great but like everyone I’d like to get the best mileage. What is the best I can expect? Thanks

I think you’re already getting the best you can expect. You’re correct, the ads you see are too good to be true.

Proper maintenance, correct tire inflation, and gentle driving are the best things you can do to maximize fuel mileage.

As mcparadise said.

One often overlooked thing (beyond the normal stuff like tire inflation, plugs, filters, etc) is the health of the cooling system. A bad thermostat or coolant temp sensor can make a mess of your air/fuel mix.

Also make sure to reduce or eliminate anything unessential that creates more aerodynamic drag - such as a roof rack.

Yup, it’s about the best you can expect. There is no magic pill or device out there.

Change the thermostat every 5 years or so.