Speedo accuracy

[Yatz]

Hi, all.
According to the speedo on my y2000 4.5 Chimaera, I am getting 28mph per 1000rpm in 5th gear. The official spec says 26. Is my speedo giving me false information or do some models actually have this ratio?

[Jordie Barretts sock]

Your speedo is over reading. Most if not all speedometers over read to a greater or lesser extent.

[jj.]

Lets just say, accuracy, speedo & TVR are not words that I would generally put together…!
jj

[sixor8]

They're more accurate than some cars I've had. Possibly because it's an electronic calculation (not a cable drive) in TVRs since the Griff Chimaera came out, mine only over-reads by about 2 mph.

I had a 1991 Vauxhall Cavalier in the mid 1990s that used to over-read by about 10 mph at 70!

[Zeb74]

I never been in UK with my Chimaera, but on the continent, the second small graduation in KPH is, in my case, underestimating the speed. This costed my 1 point on my driving license at the beginning on my owning .

[Sardonicus]

Think yourselves lucky mine over reads by 4mph according to GPS (always has) but yes like mentioned most speedo over read, later digital driven instruments on regular brand tin boxes have improved muchly over the years however

[Yatz]

What I need to find out is whether the speedo is over reading by a set amount (at 3000 rpm in 5th it is 6mph) or whether it over reads by a percentage. I have noticed those signs in restricted zones that tell you your speed telling me that I am slower than my speedo is indicating but it's not easy to look in two places at once. Not that I am strung out on notions of accuracy, it isn't erring on the side that would get me into trouble, after all, but there are times when knowing how fast you are travelling can be important. (or at least desirable)