Car Trip Information useless..

I've found that the computer calculations are way off on everything except avg mpg which has been almost dead on when I hand calculate. But the speedo is off by 3 mph. I'm wondering if they programed it for the optional 18" wheels and slightly larger tires since when I calculated for that size tire/wheel diameter the speedo would be correct. This bugs me because if the erroneous mph is tied to an erroneous odometer then I'll be loosing almost 2,000 miles of warranty by the time I hit 36k miles (actual would be 34k miles). And the miles to empty drives me nuts. When I fill up it will show 100 miles less than what it should be. It's like they figured we'd want to know how many miles until we have four or five gallons left. Nanny thinking. I want realistic miles till a dry tank.

 

Great post

 

how would one go about verifying the odometer is correct? a couple gps units and use the average miles on a drive?

Any possiblity that the computer is using the lower number used to obtain the average mpg to give a safe range? I maean it is an average number that displayed.

I would be more concerned if my odometer is off, in long distance situations that number is all I go off of for planning refuels

 

I believe that is weighted to current or very recent average MPG. Knowing a possible near empty situation on a recent trip, moving into a headwind and higher speed roadway dropped the reported range.

 

I've used the mileage markers on the freeway, but I'm not sure how accurate they are (did 100miles according to markers, 98.4 on the odometer). There used to be places on the freeway in CA that were set up for "speedometer checks" that had about 10 miles of accurate markers. Never checked an odometer on them but I used to check my mechanical speedometers periodically.

 

Download a simple odometer app on your smart phone and match to your vehicle odometer after a drive. I downloaded a mph app. That's how I found out how far off my speedo was. I got suspicious just after I bought the truck and people were blowing by me more than usual. My speedo shows I'm going 3 mph faster than actual.

 

It's impossible to get the speedometer accurate all the time because your tires get smaller as you put miles on them. If it's 3 mph slow when the tires are new it will be about right when the tires are about 1/2 worn out and about 3 mph fast when your tries are worn out. It's always been that way, we just didn't know until we had GPS. Your wheel speed sensors simply count revolutions and the computer does the math with a guess as to your actual tire diameter.

On top of that tires from different manufacturers will be slightly different in actual diameter even though they are the same size. An E rated tire, or an All-Terrain tire with a more aggressive tread is going to be larger than a street tire of the same size.

The odometer will be off by a similar amount, but over time everything evens out with the odometer unless you go to oversize tires.

It's simply not anything to lose sleep over.

 

My understanding is the miles to empty actually learns when you normally fill it up and that is sort of where it sets the miles to empty alert. Why? I don't know. My "empty alert" shows up with about 3 gallons left.

 

Not even close to that much variable due to tread wear. Especially since my brand new Firestone's have only 7mm to start with. They'll hit the wear bar in 2mm. They literally come half worn since every other car and truck tire I've bought had either 9 or 10mm new. The optional 18" and more sidewall tire package is 26mm more diameter and that makes a 3 mph difference when I calculated for those tires. I've kept track of mph accuracy with all my other vehicles for decades and I never had more than about 1 mph difference through the tread wear.

 

I looked briefly in the settings and couldn't find it. Ill keep looking.

 

You go to settings/meter settings/fuel economy/trip average.

 

You can still monitor tank average on the big dash display. Holy crap the dash is dusty.

 

A good reason to purchase new, better, taller tires, and sell the new stock tires right after purchasing the truck.

 

Yes, a guy near me is selling a takeoff set of the black and machined TRD 17" with 265/70 BF Goodrich all terrain for $800. So they're 1" wider and 3/4" more sidewall than mine. I'll have to check if my lug nuts are the same and how much Discount tire wants for TPMS sensors. According to an OEM wheel site I looked at thee are 7 1/2" wide and mine are 7" wide. Mine are 245 width and the takeoffs are 265 width. And according to discount tire the widest you can go on a 7 1/2" is 245 so I'm wondering whose wrong because the factory wouldn't put on unsafe too wide tires.