TT3 Speed

I have TT3 with their bluetooth receiver and notice that the speed it gives you in mph on screen is slower then what my car says i'm doing, does anyone else get this, and is there any adjustments i can make to rectify the issue?

A friend of mine reckons the speedos in cars tell you you're driving at a higher speed than you actually are in a bid to keep speeding down. Mind you, right after saying this he did start babbling on about grassy knolls and alien abductions...

hehehe... well it is a theory i guess.

[Stevie]

Its actually true there are set to indicate that you are going faster than you actually are, there are a few posts regarding this subject.

Oh really!! So is the GPS actually more accurate? and what speed do speed cameras work on? true or altered?, sorry i should probably go off and look for the other posts shouldn't i.

Usually all car manufacturers are (probably on purpose) not very accurate with speed instruments. This means that your car will seem faster and with less fuel consumption. The shift is usually 5-10% (so it increases with speed) but often is not linear (so it may be 5% at 35MPH, 8 at 80MPH), and I have read on some reviews that a korean car has got a shift up to 20%!!!
I don't live in UK, but in Italy the actual speed is fined, and speed control should be quite accurate. In Italy there's 5% of tollerance (in the motorway speed limit is 130KPH, but you "could" go up to 136KPH).
In my car I saw that a real 130KPH (as reported from TT and GPS) is shown as nearly 140KPH on my car.

FWIW, mine seems to be spot on regardless of speed being travelled.

Well my TT3 speed reading is identical to that of my GPS camera detector (snooper) and I'm told by them that the GPS figure is accurate to +/- 0.5 mph but with a delay lag of 1.2 seconds if that makes sense. Clearly specialist speed detector manufacturers could not operate with a dubious accuracy for speed measurement.

Against all of this my speedo is approx 5% higher constantly (Jaguar) but on my previous Ford Mondeo the difference was 10%. Also used it for a few days on a Mazda and the reading was nearly 15% higher on the dashboard (i.e. 80 instead of 70).

I've got a simple rule of thumb on it all. I drop down to the TT3/Snooper speed at cameras/speedtrap warnings/speedlimits and have never been 'flashed'

Given that the Police use 3 methods of speed detection in thier own cars in order to calibrate speeds I would imagine that the average car speedo is not particularly accurate.
I too noticed that mine was out and to be honest I reckon electronics via satellite should be more accurate than a physical car speedo which is supplied with information via a cable.
I'll stick to believing what my GPS tells me. ( but then I do drive a Skoda ) !!!!