My speedometer reads 5 mph over at 80 mph (really 75 mph). The car will be in for a service when snow around here finally goes away. Can this be corrected or at least be brought closer to reality when it's at the dealer?

 

By law German cars can never read low, so they are set up to show a higher speed than you are actually going. I believe the max over then can read is 10% +4 mph, yours is within the tolerance allowed.

 

You'll have to ask the dealer/tech this question. I know the speedo reads optimistic more often than not, and 5mph is not unheard of. (My 02 Boxster exhibits this 5mph optimism, while my 03 Turbo's speedo only reads 2mph over.)

But I've never explored having the tech do anything about this. Early on I checked the odometer and once I was satisfied it was well within being acceptably accurate: 0.2 mile error over 200 miles or +/- 50 miles over 50,000 miles (the warranty miles); I just lived with the error.

 

Asked my dealer about it and he said would have to take out the dash to fix.....I don't know why you could not do it with programming so told him I can live with it. Just have to remember when I drive.

 

On my way to the airport this afternoon, my Audi was off by 1 MPH at 80. Not reading low being a German law makes sense to me however, a precision instrument like a GT3 being 5 MPH over at 80 I find truly bizarre.

 

If u doing 75 mph which means 70 mph chances are u won't get nailed by highway patrol.
So believe what it reads u may not get nailed. Another tip as well if u going faster than u should never brake to slow down- it's admission of guilt. I've done 90 mph( really 85) on a 65 mph zone never braked never got nailed. Mike

 

For goodness sakes do not double check the coolant gage against the actual real time coolant temperature or the oil pressure gage against the actual real time oil pressure. And not to pile on but the tach probably isn't real accurate either.

Relax. Just mentally do the math to drive at the proper speed and enjoy the car. In either of my cars I just note the error and set my speed accordingly. It is just automatic to me now, has been since about day 2 of my ownership.

 

Not getting my nickers in a twist, love the car, would like to get this fixed if it's an easy fix. If not, I'll live with it.

 

Every car you, I or anyone else has ever driven has the same built in safety net of error. Just get over it. Its there for your benefit by law against the law as others have suggested.

What will you do when your tyres wear or you fit different makes/type with differing rolling radius', will you re calibrate every time and every few hundred miles... sorry, just madness

 

a precision instrument ? dude...it's a car

 

My Audi's are spot on. Porsche should be too. With NAV installed, they can get GPS speed and use that to calibrate the actual speed readout. No excuse for such large errors. I don't want to have to continually calculate, i.e. the limit is 65, 20 over is 85, but since the speedo is off I could really creep up towards 90 ...

 

I had a case of the opposite effect. I was going XXX MPH (to pass safely, of course) and suddenly saw a police trap on the horizon. I stabbed the brake and passed the trap at speed limit. They stopped me a mile later, and a cop says "Why where you going XX in 65???" I barely kept myself from smiling, because the speed they registered was thousands of dollars cheaper.

 

You do know they can do you for speeding at or under the limit if the officer believes it was to fast for the situation/conditions? Why would you want to habitually speed to the Nth degree, seems like pushing your luck as well as other fellow motorists around you...

 

Why?.....five words......it's fun to go fast
Habitually......not sure about that.

 

I believe the manufacturers set the speed indicators to read high purely and simply to extricate themselves from lawsuits where the operator states that they were using Cruise Control set to the speed limit.

I am not sure what year this actually came about but its been around for quite some time now.