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Gas Milage

Why would a 2006 Dodge Grand Caravan suddenly start to get less Mpg. It went from 22 around town to 20 mpg. We had it checked by our mechanic and all he did was change the air filter. He said everything else was fine. This mpg is without the air conditioner on. It drops to 18 with the AC.

The revised EPA estimates for you vehicle are 16 or 17 MPG city and 23 or 24 MPG highway. Depending on if you have the 3.3L or 3.8L model, 20 MPG is right on the money for what you are supposed to be getting. Also in order to be accurate you can’t go by just one or two fill ups. Average your mileage over 5 or more fill ups to get an accurate picture. But with that said your current mileage falls into the realm of what your vehicle is expected to to get. I doubt if there’s anything wrong with it.

It could be: tire pressure, wheel alignment, sticky thermostat, dragging brakes.

Did you change your driving patterns? How many tanks did you go through to determine the drop in mileage?

How do you measure that mileage. Are you using an onboard computer readout? Those MPG are certainly close to normal sampling errors.

Did your area switch to reformulated gas or gas that contains ethanol? Did the place where you habitually buy your gas from recalibrate their fuel pumps? Are the red lights longer than they used to be? Taking a different route to work?