Baruccheri

Alright,

Small issue - I bought my car (08 A4 2.0t quattro) last year from the dealer brand new, used to pass a mobile radar detector unit everyday and going a constant speed, my speedometer would say I was going about 3 or 4 mph less than what I was going. Didn't think much of it but then I tried a mobile gps unit that tells you your speed - same thing, roughly 3 mph slower than what my speedometer was telling me.

Any thoughts on this? The issue just kind of bothers me but never enough to do anything about it.. anyone ever have a similar issue or know the cause?

Also, would an ECU upgrade potentially fix this?

Thanks.

sTrucTural PE

My speedometer is off by 3 or 4 mph, too... if my speedo says 75, I'm really doing about 72 per my gps. I hadn't really thought about it, I figured it was just the way it was. I have Revo tuning and it didn't fix this.

A4Audi4Fun

Normal - there's a tolerance level allowed on the speedo display accuracy and Audi / VW have chosen to display a reading that is slightly higher than actual if you do the math it's probably in the reading +5% higher range.

Baruccheri

That kinda sucks... so do all audis/vw;s do that or is it just kinda random?

makav3li

mine does it too, im not really upset about it because i usually cruise 10 mph over the speed limit so if its really only about 6 or 7 mph's about the limit theres alot less chance of me getting pulled over so I'm not complaining.

Baruccheri

Yeah, I rationalized it the same way, I'm always over the speed limit... im generally breaking the law when i throw it into second.. but, none the less, I would prefer is to be accurate... but, whatever... it was a small issue that I had in the back of my mind and now I know it still is a small issue and nothing to worry about... Thanks for the input guys, put me at ease!

Steve Mac

My 06 also reads 2-3 low. It originally read 3+ low but differences in tire diameter (even at the stock size) mean you can vary somewhat. FWIW, my wife's Passat (04) also reads 3 low. But rentals I have had have read spot on, so it's not everything everywhere that's low.

rjkotler

I have the same issue. 3-4 mph slower than the spedo indicates. I have heard that you can have it calibrated to reflect a change in wheel size but I have not looked into it.

I am going to ask the dealer about it at my next service and will share the results.

Baruccheri

Would greatly appreciate that, thanks!

Pete@ECSTuning

My A4 reads slightly lowers ~4mph. I got larger diameter tires and it is now spot on.