You get a speeding ticket when your speedo indicates you aren't speeding.

That would hurt and I would sue the hell out of the manufacturer.

 

Manufacturers always err on the side of showing a faster speed than your actual speed for this reason, so the concern is pretty pointless, unless the speedometer is not functioning as designed.

 

Yes but they're screwed eitherway. If they err too slow people get tickets and complain. If they err to fast, owner's warrenties run out early, and/or lease penalties are inflated. Of course they could make it right (within 0.5%). I could see tire condition changing the reading, but 3% is a bit much.

 

Thats why on the highway I always go 5-7mph over the limit even when I see a cop. Their radar detector has control limits just as our spedometer. I figure there is around a 5mph gap.

 

Mines right on as well, even with my GPS showing exactly the same

 

On the STi the speedo reads ~ 5% too high (probably for the aforementioned liability reasons) but it has been shown that the ECU and odometer know the "true" mileage. fwiw.

 

The solution is not that difficult to grasp, err on the side of caution for the speedo, but include 3% leeway on the warranty to cover this potential gap. No complaints from anyone on either end of things.