ratledge

I have taken a 7000+ mile test to calibrate the actual versus shown milage in my '02 I35 (non-sport) and found some amazing facts!

First of all, after 7120 miles, my indicated mileage was 26.9mpg, but actual measured was 23.65mpg. Of course, I was using the mileage the car trip computer logged to make the computations. I realized after trying to follow several computer generated maps that I was getting more distance than the trip computer gave me credit for... So, I took the time to measure 10 2-mile segments on the Intrastate and came up with 1.9 miles every time! I did a long-distance trip that should have come up 360 miles, and it said I had only traveled 342. Bottom line: it is giving me 5% less mileage on the odometer than I'm driving - no joke, consistent, every day, every mile. I guess the good side is this means I'm actually gettin slightly better than 5% more gas mileage or closer to actual 24.83mpg - not too shabby, really (I'm a pretty sedate driver - handicapped, just wanted to have a nice ride, not a speeder). That's less than 10% of instead of the 15-18% I've been insisting all along. (well, I'd get 26 on the highway, and it would measure 29 or so, etc. - this means I was actually getting closer to 27.3mpg)

Also - that means that I'm getting a 63000 mile warranty as well.

Does this hold true for everyone else? I always use 93 octane gas, and change the oil every 3000 miles like a good little boy...

InfiniSteve

iTrader: (1)

Check your tire pressure, also do you have the correct size tires? 5% off could mean your tires are bigger than OEM or over-inflated.

A-RokI30T

i don't believe tire pressure has much to do with the actual mileage, i think it has more to do with gas usage. without proper pressure car is less gas efficient. and as far as tire size goes if it's a 2002 I35 i'm assuming you purchased it new? it shouldn't have anything but the proper tire/wheel size from the factory. if you want you can go to a infiniti dealership and have them check your computer see if maybe something is not right. i've seen that problem a couple of times at the infiniti dealership i work and it's always computer issues that can be fixed in minutes. hope that helps

ratledge

Original factory tires - Bridgestone OEM. My dealer, like many others claims that the trip computer's numbers are "estimates" and refuses to do anything about adjustment thereof. I have complained since "day one" about the misguidance provided from same - and been told that there is no fix.

The tire pressure is constantly monitored by using the funky red/yellow/green twist on pressure indicators.

This vehicle is exactly as it came from the factory - no mods to the tires, suspension or similar. Bridgestone "Turanza EL42" HR rated 215/55 17" on factory rims.

InfiniSteve

iTrader: (1)

Even though this isn't your current problem, I think inflation could affect the readings. Overinflating could increase the diameter of the wheel. The car reads mileage by rotations of the wheels. That means if they are bigger they will go farther per rotation thereby your speedo is off. I'm really not sure how much inflation could affect the readings, my guess is under 1% anyway.

ratledge

Well, I agree- overinflation would decrease the readings, because the wheels would turn less to make the same headway - but this is not the case... My tires haven't changed nor have I even had a flat (knock on wood!) in the past 20 months (I've got a fairly 'early' October '02 model with about 35K total miles on it - I live 35 miles out-of-town.

InfiniSteve

iTrader: (1)

Sorry to hear man, I look at it this way, at least your car has a trip meter! My 98 I30 has nothing indicating mpg or how much mileage on a tank left! I would love that even if it weren't 100% accurate. Still I think it's not right how Infiniti won't fix the issue. Makes you think if they intentionally created this problem (for test drivers).

PAREDLINE

You have too much free time on your hands