You'll need a flat stretch of road where you can set your Cruise Control for a few minutes.

1. Press the Info button to bring your Multi-Display readout to Avg. Speed.

2. Set your Cruise Control at whatever speed you're comfortable with.

3. Hold the Info button to clear the Avg. Speed readout.

4. Wait 10 seconds and compare the new Avg. Speed readout with the speedometer reading.

Try this a few times and see if the Speedometer and Multi-Display matches.

My speedometer reads 1.5-2MPH faster than the computer in the Multi-Display.

Interesting...Which is correct? or are they both wrong?

Does anybody really know what time it is? Does anybody really care?

 

Paddy Wagon, I've been testing with my computer readout like this too. I got the idea from a Car and Driver article that did a whole spill on speedometers. In a nutshell, your speedo is off (reads faster than you are actually going) and your odometer is actually much more accurate - as is your avg. mph meter.

Pretty cool trick though...good question!

 

Well, I guarantee I'd rather have the speedometer read faster than slower.

A few years ago, I bought a used Ford truck with oversized tires. The 2nd day of ownership and I get 2 speeding tickets in one night. I thought I was 5MPH over the speed limit, when I was actually 12MPH over. I managed to get the judgements lowered with a receipt from the Dyno Guy, but...Sheesh!

 

I guess I don't have to explain to you why manufacturers do it then It is deliberate and the amount of error varies from car make to make and from country to country.

There is a law in Europe, I believe, that your car cannot read slower than you are actually going so more error is built in so that a wider variety of wheel/tire combos can be used.

 

Well, it looks like I have another good reason to buy
the 18s I want. They should correct this problem.

Mebbe those L-Sportline 18"s.
<Counting Pennies>Hmmmm....</Counting Pennies>

 

Yeah...I need a LOT of pennies

Thats another good thing about 18's with 255/55's. The speedo becomes more accurate.

 

Howdy folks.....

Wanna know how fast you are really going???

Other than driving into a law man's radar??

I use my GPS reciever and look at the speed-o-meter screen.
I even tried it with two GPS's and it is very accurate.

Currently running Michelin Cross train's, factory size, + or - 1%...

From the desk of beaker....