# Does the Trip Computer Lie About MPG?

idavidson
Posts:

**41**
Just took possession of new 2008 LS with V6.

Only 40 miles on the clock when I took it.

Reset the trip computer and began the 160 mile

drive home all highway.

At the end the trip computer stated:

Average speed: 57 mph (this is true since I babied

it the whole way down).

Average mpg: 34.2

This last figure sounds bogus since the v6 is rated

by the EPA 20-30 mpg and no one has reported

such a high figure before. Could it be wrong?

It was just me in the car cruising at 55 mph for

a bit then 63 mph for a bit and so forth. Never

reved the engine about 2700.

Only 40 miles on the clock when I took it.

Reset the trip computer and began the 160 mile

drive home all highway.

At the end the trip computer stated:

Average speed: 57 mph (this is true since I babied

it the whole way down).

Average mpg: 34.2

This last figure sounds bogus since the v6 is rated

by the EPA 20-30 mpg and no one has reported

such a high figure before. Could it be wrong?

It was just me in the car cruising at 55 mph for

a bit then 63 mph for a bit and so forth. Never

reved the engine about 2700.

Tagged:

This discussion has been closed.

## Comments

39941turn off that feature).

This morning I drove 1 mile to get on the freeway (said it

used about 15 mpg) then 25 miles on the highway at 55 mph

(the average mpg crept upto 33mpg) and then one mile on suburban

streets to get to work (average mpg crept down to 32.5mpg).

Could it be because I'm babying the engine? It's in the burnin period

so I'm accelerating very very slowly. Just staying in the right hand

lane, not overtaking, steady at 55, 58mph. Getting lots of fingers and

rude signs, but that's another story!

399turn off that feature). "

I have a 2007 and I found that while the manual described a way to change it, the mode resets when you turn off the ignition, so I was always back to square one. Many people (at least with 2007s) are frustrated that you can't keep a running total average MPG over a tank if say that tank takes you 5 days . (to be able to get up in the morning and still find it at the last reading of say 25 cumulative MPG, vs going though it displaying like 15 mpg till you have driven maybe 20 miles to bring the new average back up) If I drive it enough miles on the highway before shutting it off the reading is pretty close to what you actually are getting by taking the trip odo miles divided by the fill up gallons, but otherwise the indicated MPG will be much lower than actual (not enough time so display a real average)

Note that I do not have the Nav package, which I believe gives you better access to programming features.

99841> never gotten above 29 MPG. (2007 LS V6 4WD)

Okay, so its not out of the realms of possibility since mince is a 2WD.

Also, it was just me (200 pounds) and nothing else.

41Just finished my first tank of gas.

404 miles, 12.5 Gallons put me at around 32 mpg.

But as I said for the first 300 miles I babied the engine.

As an aside I did two experimental trips:

25 highway miles at 55 mph: I got 35 mpg according to TC.

25 highway miles at 50 mph (the manual recommends this as

a speed to maximize fuel economy): I got 40 mpg.

But let me tell you that driving at 50 mph on CA highways is

dangerous!!!

6015I don't think it's fair to quote anything but the mileage that you've calculated based on miles traveled / gallons used. Anything else is phony.

41But it seems that the trip computer is fairly accurate approximation

to that based on what I've seen.