Poor gas mileage problem easily solved. D'oh!
 

Following my recent first oil change, I complained that my gas mileage had dropped (by about 10 percent), and no amount of careful driving would bring it back up.

Well, today I found the problem, and it had nothing to do with the oil change. In just three months, my tire pressures had dropped from 40+ PSI to just 28 PSI. I've never experienced such a quick drop in pressures in any car.

This is a heads-up for you to check your pressures much more frequently than you might expect.

The good news: with my tires at "healthy" pressures again, the increased fuel efficiency is immediately obvious. Formerly traveled routes are now giving me the same excellent MPG that they did before.

Maybe I'll see a mileage boost, as well, due to the new synthetic oil?

Note: my tire sensor warning light NEVER showed low pressures. When I reviewed the procedure carefully (page 168, in the manual), I noticed that you must leave the "Power" on for several minutes after resetting your tire pressures. Make sure you follow the procedure exactly. A final re-reminder to newbies: you MUST reset your tire sensor any time you change your baseline tire pressures, or the sensor will not work properly.

Tomorrow I'll be driving several hundred miles, and will confirm the gas mileage figures. Go check your tire pressures!

Re: Poor gas mileage problem easily solved. D'oh!
 

Steven: The serviceman my have reduced the tire pressure because most sedans use 27 or 28 psi.

Re: Poor gas mileage problem easily solved. D'oh!
 

Good point, David. I'll bet that's what happened, and it would explain the sudden nature of my gas mileage drop.

Re: Poor gas mileage problem easily solved. D'oh!
 

ya the manual also says the MAXIMUM pressure should not exceed 35 PSI where the maximum speeds are 160 KMPH or lower depending on your countries driving laws.

Re: Poor gas mileage problem easily solved. D'oh!
 

When I took mine in for service (both times) they set the pressures at the 32 psig listed on the door post. I run at about 36 psig.

Re: Poor gas mileage problem easily solved. D'oh!
 

I was wondering what people run at. I have mine at 33PSI with the Bridgestone.

Re: Poor gas mileage problem easily solved. D'oh!
 

The TCH door sticker says that the tire pressure should be set at 32psi. Since the standard Toyota service include tire check, that means the service techinican definitely reset the pressure to what it's "supposed" to be. Even when I've told service techs not to check my tire pressure, I've found it adjusted.

Re: Poor gas mileage problem easily solved. D'oh!
 

I got the nifty michelins!!!

Re: Poor gas mileage problem easily solved. D'oh!
 

I run 42 psi on the front and 40 psi on the rear. Tire wear has been very even so far (5,200 miles). I also have the Bridgestone tires :)

At my 5K service the tech reset my pressures to 35psi, my request to leave them at 42/40 not withstanding:(

Re: Poor gas mileage problem easily solved. D'oh!
 

Anyone who might be interested in topics about over-inflating tire pressures (or any topic, for that matter), first try doing a keyword search in the forums. There's a good chance that your topic may have already been discussed, and re-discussed. So much good information and documentation lies dormant in the annals of greenhybrid.com.

Re: Poor gas mileage problem easily solved. D'oh!
 

I had my Michies set for 36psi in mid June. I checked a week ago and they had fallen to 32-33psi across all 4 tires. No one has touched them but me. I suspect cooler temps and a bit of normal escape were the cause. The overnight temps around here have fallen off from around 20C (70F) to near 10C (50F). We'll be into freezing overnight temps in another 6-8 weeks so that's about when I'll try to remember to check them again. The first TCH winter cometh, it will be interesting to see new winter related threads start appearing on this forum.

Re: Poor gas mileage problem easily solved. D'oh!
 

Based on all those prior threads, I increased the tire pressure on my Michelins from 32psi all around up to 38psi during my last fillup. But I have not noticed any increased FE on this tank of gas, even though I drive the same roads every single day. In fact, I seem to have lost 1mpg, as I was consistently getting a 37mpg reading on the computer, and now I'm getting 36mpg (although I am attributing that to some increased highway traffic that I've experienced the past week.) On the next fillup, I'm going to go up to 40psi.

It would be interesting to correlate higher tire pressure with the specific tires (Michelin vs. Bridgestone) for each person that is doing this.

Re: Poor gas mileage problem easily solved. D'oh!
 

At 40+ PSI, I got 44 MPG on my trip this week from San Diego to LA and back (about 240 miles, including errands), according to the instantaneous readout. Speed was 65-70 MPH, with A/C running in ECO mode 100% of the time. Now, we'll see how city driving and short trips will ding me during the rest of this tank!

Re: Poor gas mileage problem easily solved. D'oh!
 

Just bumped my Michlin's to 40# form 36# but have not driven it since.

Re: Poor gas mileage problem easily solved. D'oh!
 

I've been steadily increasing my mileage with each tank. First one was 36.4 and when I filled up yesterday my last one was 43.5. At the same time I increased my tire pressure from 32 to 40 psi. My current tank is 46.2, but with less than 50 miles it's way too soon to say what, if any benefit I'll get.