Grizzly old man

When we took our trip to Tennessee this fall the mileage computer was darn close to what I worked out on paper.

The over all trip worked out to 31.1 mpg. The computer varied between 29.8 and 31.9.

Paper and pencil are the only way for me to believe these new fangled computer thingys.

Now having said that the mileage computer in our ‘98 LHS is so accurate I don’t even bother to figure it out on paper. But the Miles Till Empty thing is almost always wrong.

When you get in it might say you have 357 MTE and it might work out to being 135. It all depends on the road you travel I guess. Lots of hills, like going to Tennessee, eat more fuel.

When we went out to Nebraska, when the wife’s dad was still alive {he was born out that way and we ended up driving him to the last family reunion he attended} we did not have much of anything for hills so we got closer to what the computer predicted.

Of course the car was almost new then and probably ran better. Still the best mileage I’ve ever see on that buggy is 21.5 mpg.

Old Lar

I drive with the average mpg DIC on. The 06 doesn't have the instant reading. Mine always reads low by 1-2 mpg vs the calculated values. I alway liked the instant reading that my 99 Buick had as it teaches you how to drive to maximize your mpg.

The avg reading tells me how everything is going in the long run.

I replaced my Goodyear assurance max tires with a set of Cooper tires and have noticed a drop of about 3 mpg from my overall average since the tires were installed. Right now I'm saying that I don't have a big enough sample size since the new tires were put on.

The long term mpg has been 31+/-2.8 mpg. (fillups 109)Roughly 39,000 miles. Currently it is running 28+/-0.9 mpg. (fillups 8)Roughly 3000 miles. Statistically the values overlap with their ranges.

donbrew

It is an '08 220,000 miles, I do about 65,000-70,000 a year.

5speed4

Same here. I've got an '06 that reads about 1.5 mpg lower than the calculated fill up values.

SS fan

It is an '08 220,000 miles, I do about 65,000-70,000 a year.

WOOOOHOOO, cool Keep on trucking, I'm trying to catch you, but I only do 40,000 a year, old age I guess.

donbrew

Do you have the OEM size tires? I found that when I put the 215X60R16's on instead of 215X55R16 (because they are cheaper) that is about the error (3% on the odometer). Thus my earlier comment about the tires that the computer thinks you have. With my mileage I don't really care if the car has an error showing less than actual.

deliveryman

Are the 60's cheaper than the 50's on the tires? I may have to check on that because I replace tires about every 6 to 8 months. I drive about 100,000 miles a year and I have an 09 ls with 227,000 miles right now. My speedometer is about 2 miles per hour slower than what my gps shows with the stock size tires.

5speed4

Not only do I have the OEM-size tires, I have the OEM tires.
They've got 57K miles right now (about ready to replace them). If anything, they're smaller than the computer thinks due to the wear. Mine is a 2LT with 215-50R17s, btw. When I replace them, I'm planning on going with 225-50R17s because I like a little bigger tire (fill the wheel wells) and that's the biggest that will fit in front under the spring perch. That will make the DIC off even further.

Black C5

Quote:

Originally Posted by firemangeorge

And the instant mpg on the DIC is a waste of time and computer innards.

While the instant mpg may or may not be 100% accurate, it can help you to learn what driving styles can produce the best mileage. If you are not in a hurry it can be very helpful to determine at what speed and condition yields the best mpg, even if not 100% accurate. I know that at 80 mph with cruise control set the instant readout says 22mpg and at 65 says 35. While those numbers may be a little off, it encourages me to drive a little slower if I have the time.

There is plenty of computer power that isn't even used, so this capability being included does not take away from any other useful function -

Black C5

Quote:

Originally Posted by Old Lar

...I replaced my Goodyear assurance max tires with a set of Cooper tires and have noticed a drop of about 3 mpg from my overall average since the tires were installed...

Are the new Cooper tires the same diameter?
Have you measured them?

Different tire manufacturers produce tires of different actual tire sizes for the same tire spec. A larger tire diameter will result in a lower MPG readout, but not necessarily more gasoline per mile traveled.