I was unsure if my speedo had been properly converted to mph as the mileage is counting up in K's. So I used my tom tom to measure the speed, and to my complete surprise the speedo was reading exactly the same as my sat nav :shock:. In total I drove around 80miles and the speedo was correct all the way. I've never had a car that's had such an accurate speedo! From my experience they're normally around 5% - 10% out.

 

From all the talk of inaccurate oem dials on the site I thought I'd post up some good news. lol..

Yep found my speedo to be very accurate.

Will depend alot on wheel and tyre size too ;)

Mine is perfect as well, when i get over 100mph it seems to do a few miles out (on a private track of course)

Mine is so far out over 40 mph that I can ONLY use tom tom to guage my speed.

 

When the speedo says I am doing 70mph - I am actually doing 82mph! I thought maybe my tom tom was out, but I was so worried I checked it with a Navman and it was the same.

 

I think this must be since I switched to 19" wheels.

 

And to think - on my last track day I got up to 6k rpm in 5th gear which felt really fast, but was only an indicated 125mph - wonder how much it was out by at that speed?

I was unsure if my speedo had been properly converted to mph as the mileage is counting up in K's.

 

You sure its counting up in k's?:nelson:

Mine is so far out over 40 mph that I can ONLY use tom tom to guage my speed.

 

When the speedo says I am doing 70mph - I am actually doing 82mph! I thought maybe my tom tom was out, but I was so worried I checked it with a Navman and it was the same.

 

I think this must be since I switched to 19" wheels.

 

And to think - on my last track day I got up to 6k rpm in 5th gear which felt really fast, but was only an indicated 125mph - wonder how much it was out by at that speed?

 

Well according to this speed calculator: http://www.240edge.com/performance/top-speed-calc.html

 

Assuming you were in a TT manual on stock UK 245/45/16 rear tyres at 6000rpm your speed was 159mph :D

 

Data used:

 

Revs 6000

Tyre width 245

Profile 45

Rim Diameter 16

Final transmision gear 0.752 (5th gear)

Diff ratio 3.69

Well according to this speed calculator: http://www.240edge.com/performance/top-speed-calc.html

 

Assuming you were in a TT manual on stock UK 245/45/16 rear tyres at 6000rpm your speed was 159mph :D

 

Data used:

 

Revs 6000

Tyre width 245

Profile 45

Rim Diameter 16

Final transmision gear 0.752 (5th gear)

Diff ratio 3.69

 

what about with his 19"s?

You sure its counting up in k's?:nelson:

 

Yes mate, I drove to my sisters and back 82 miles in total. The trip counter said i'd done 130 odd, which works out at 82 miles.

Mine is so far out over 40 mph that I can ONLY use tom tom to guage my speed.

 

When the speedo says I am doing 70mph - I am actually doing 82mph! I thought maybe my tom tom was out, but I was so worried I checked it with a Navman and it was the same.

 

I think this must be since I switched to 19" wheels.

 

And to think - on my last track day I got up to 6k rpm in 5th gear which felt really fast, but was only an indicated 125mph - wonder how much it was out by at that speed?

 

 

Something very wrong with yor speedo. If your wheels go bigger the the more accurate you speedo will be. What tyre size are you running?

 

As mine is within 1mph on track days?

what about with his 19"s?

 

He's only just bought those, I'm not sure what size wheels he had on when he did that, possibly 17"s

 

He'll be here soon enough to clear it up though :D

Yes mate, I drove to my sisters and back 82 miles in total. The trip counter said i'd done 130 odd, which works out at 82 miles.

 

Mine shows MPH and counts up in KMs too

He's only just bought those, I'm not sure what size wheels he had on when he did that, possibly 17"s

 

He'll be here soon enough to clear it up though :D

 

Yes I had a set of 17" momo arrows before...

 

it might be down to the replacement dial face I stuck on the dials instead of the wheels....