A brief history first. Had the car for about 8 months now and has about 2400 miles.

First time it happened was when i had the car serviced for the first time a little over a month ago to change the oil and have the passenger seat recalibrated cuz i changed to MR seats. Distance between dealership and my house is about 8 miles. Upon getting home it showed an average MPH of only 8 miles and average MPG was 12.

Used the car a couple more times after that and it was fine.

Drove it this friday to a party and it was fine, a 20 mile drive. On my way home at around 1am my average MPH was only 12 and my average MPG was only 18.

Has anybody experienced this?

 

Those are averages...

How are they wrong?

 

yeah your not really going to be getting over 18 MPG and the speed is an average of the all the miles on the car except if you reset it

 

Wow. Read your owner's manual. You're mistaking average MPH for a trip odometer.

 

oh and i forgot to say my average MPH is 25 and i have over 15,000 miles on the car

 

maybe i didnt explain it clearly?

on my trip to the party my average MPH was over 30 with a little bit of traffic and got an average MPG of 23. When i got into the car after 5 hours its all back to zero, no traffic and got home only averaging 12 MPH and averaged 18 MPG.

 

Mines off too man. I drove back home at 90mph from Florida most of the trip and it said my average was around 40 or so.

 

The meters reset after 4 hours of the car being off.

They arent wrong, you're averaging those values.

 

so i am averaging those values when i am in the car and i know i am driving hella of a lot faster with no traffic and got 12 when going there i was able to average 30 with traffic?

i may drive slow but not that slow to average 12 mph.

 

why even pay any attention to it. its not important. just use simple math to figure it out if you really want to know

 

If your car is running and not going anywhere, it will effect your mpg and average mph. It calculates both when the motor is running. The car doesn't need to be moving. I have a diesel truck I'll turn on so I can run the AC while taking a lunch nap. In an hour I'll lose roughly 1-2mpg on my average mpg display, depending on how long it's been since I reset it. If you've recently reset your mileage display, and sit at a stop light, you can also watch it tank.
Having said all that, I've never seen an MPG that gave a truly accurate reading anyway. Usually they're optimistic, and that's fine by me.

 

^finally a logical post than people just blabbing their mouths. thanks

 

Lol, blabbing our mouths? My first response was your answer.

Dont get mad at us because the concept of averages is over your head.

 

maybe next time READ and then UNDERSTAND before posting so you could post something beneficial like what fastkevin did. rather than trying to increase your post count.

thank you very much you can come down on your high horse now.