Lately my 2002 has been reporting reduced mpg's. nomally I average abou 47 on the computer, lately barely manage 44. It has been very windy here the last few months, but it seems the more I try to baby it to squeeze out the 47+ the more I seem to score 44mpg! Frustrating! I could blame the new tires which are not LRR but on a calm day I can still score a 46 without trying. Also I don't think there's anything wrong with the battery system as it still drives to level 5 in a parking ramp, and will drive with the motor shut down up to 35 mph. Could this dang wind really be the reason? or could I blame low quality fuel? maybe it's time to have the carbon cleaned out of the intake? don't think so, it runs smooth as ever... alignment checked out normal when I bought new tires. I've never seen it so windy for so long, nor never saw my 2002 Prius use so much gas in warm weather. Tires? wind? what ?
I would suggest pumping up the tire pressure in front to the max psi rating that is listed on your sidewall of the tire. 40? then 2psi less in the rear. It causes a little bit of a bumpier ride, but that is what most folks on the forum do.... New tires will cause you to take a small hit in MPG. And the wind will cause some MPG loss as well. The windier it is, the more resistance there is for your car to move. Sounds like your car is just as healthy as it can be. Unfortunately, two of the small things that can impact MPG, is happening all at once. Once the new tires get broken in and the wind calms down, you will see you MPG bump back up a couple MPG....
Tyres for sure and I bet the mpg's don't improve much even once they're run in. I talk from own experience. I asked for llr tyres but got the same brand and model tyre but not llr. My mpg's took a hit and I just couldn't get the figures I used to get with ease, however hard I tried. Dealer informed me to let them bed in etc etc but after 2k miles still the same mpg's. Turned out the llr had been ordered but not sent so the offending tyres were removed and replaced. My mpg's immediately went back up to where they were and there was no hit on the mpg's for braking them in. I did the sums and noticed that it is worth paying for the llr tyres.
Well, it's been so darned windy for so long it was hard to distinguish any immediate change in Mpg when the tires were put on. That would be my fault, wanted to slap on some tires to get us by till we trade the car in next fall, the old ones were no longer "legal". I did inflate them to 40 at first but they howled so loud I had to cut the pressure back to 35 all around. I may try pumping them back up again and see, don't know how long I can live with "only" 42 mpgs. haha.
