My Prius is doing something I don't think it should do

<div class='quotetop'>QUOTE(kayemarschke2 @ Mar 21 2007, 08:32 PM) [snapback]409908[/snapback]</div>

I suggest you stop looking at the screen so much and concentrate on the road ahead. (You can switch off the screen altogether if it distracts you). Before you start a journey press the "Reset" back to zero and then at the end of your journey make a note of the MPG for that journey. Do this several times and you'll soon have an idea of what your average MPG is in different conditions. There is one 10-mile trip I do regularly with the CC set at 50 mph. Outwards it entails a slow incline upwards to about 700 feet and then downwards to my destination. For this I usually get a reading of about 55 mpg on the outward journey. On the way back it is always over 70MPG!

 

<div class='quotetop'>QUOTE(Oxo @ Mar 22 2007, 07:54 AM) [snapback]410086[/snapback]</div>

I am approaching my second fill-up. I seem to be averaging about 44MPG. My daily commute is all highway at 75-80 mph. Relatively flat. Total miles on the vehicle is about 775. As soon as I got the vehicle I replaced the stock tires with Michellin Pilot Exalto A/S 195/60 R15. The tire place would only inflate to 34psi and said that I could deflate to 32 if I thought the ride was rough. I'm reading on here that I should have the inflation up to 42/40 (max inflation on the exaltos is 44). How much will that really help?

c.

 

<div class='quotetop'>QUOTE(chrisg67 @ May 18 2007, 11:41 AM) [snapback]444934[/snapback]</div>

Your numbers seem totally reasonable for the type of driving you're doing. You're getting worse mileage than some people here for a few reasons: you're driving faster than is optimum for great mileage, your tires have lower inflation than is optimum for great mileage, and you replaced your OEM tires with tires which are probably not designed for low rolling resistance (although, maybe they are; I haven't gone to look it up). Note that, while the OEM tires are pretty crappy, they are good for fuel efficiency. If you were to inflate your tires to 42/40, you would probably see a modest increase in MPG (maybe up to 46 or 48 MPG); there is absolutely a measurable improvement in gas mileage that comes from inflating your tires more. Another bump would come from reducing your speed, but many people (myself included) are not willing to do that for better mileage.

 

<div class='quotetop'>QUOTE(Betelgeuse @ May 18 2007, 01:09 PM) [snapback]444963[/snapback]</div>

After I filled up for the second time, the mpg increased to 46.5 (+1.5mpg). I noticed an increase after the first fill (+1mpg) up but didn't think much about it, because I was still learning to drive the car. I will increase the tire pressure and that will get me 2mpg or so. The Exaltos are not LRR per se but they aren't horrible and they are way better than the Incrapities in just about every other way.

Either way, if I don't get any better than I am right now, I'm still getting more than 3 times what I was getting with my pickup truck (12.8mpg - yikes!).