njc021073 Posted January 31, 2005 Report Share Posted January 31, 2005 Since I have been using my GPS, I have realised how inacurate the Speedo in my 2.0 TDi is. At speeds above 60mph it is 5-7mph out. An indicated 80mph is in fact only 73mph I have not only checked against my GPS, but also by timing using a Tachymeter and motorway marker posts. My Passat TDi 130 is only 2 mph out at 80 (actual 78mph). If VW can manage good accuracy, why can't Audi. Does mine have a fault? A simple way to check is to drive at 70mph, and assuming you have the 6 speed, it should be indcating 2100 rpm. Mine is just under 2000rpm which is well out Link to comment Share on other sites More sharing options...
UBM Posted January 31, 2005 Report Share Posted January 31, 2005 The Audi's all seem to overestimate by 10% exactly! Link to comment Share on other sites More sharing options...
Paul Posted January 31, 2005 Report Share Posted January 31, 2005 [ QUOTE ] A simple way to check is to drive at 70mph, and assuming you have the 6 speed, it should be indcating 2100 rpm. Mine is just under 2000rpm which is well out [/ QUOTE ] surely thats to do with gearing /final drive not speed.? easiest test is 60 mph for 1 min. you should cover 1 mile. Link to comment Share on other sites More sharing options...
Tomk Posted January 31, 2005 Report Share Posted January 31, 2005 yes i get the same thing with my GPS - 80 on speedo = about 73 on gps Link to comment Share on other sites More sharing options...
Scotty Posted January 31, 2005 Report Share Posted January 31, 2005 Strange - my S4 and many on Audiworld are a lot more accurate than that. From 0 up to tripe digit speeds I've never found mine differs from my GPS by any more that 1-2mph. Link to comment Share on other sites More sharing options...
UBM Posted January 31, 2005 Report Share Posted January 31, 2005 Mines based on gps too. 70mph on the dash and 63mph on the gps. Link to comment Share on other sites More sharing options...
scooby_simon Posted January 31, 2005 Report Share Posted January 31, 2005 I think there is a fair variance on speedo's. My scooby is about 10% out (80 = 72) on GPS, Wife's V70 is only about 2 mph out at 70 ! Link to comment Share on other sites More sharing options...
njc021073 Posted January 31, 2005 Author Report Share Posted January 31, 2005 The final drive for the 6 speed box in top gear (both for my A3 and Passat) gives as near as damn it 70mph at 2100rpm, so anyone else with the same box can quickly reference it. The best way is to use the posts on our well maintained motorways (although they are spaced 100 meters appart, so it gives a KM reading) and a tachymeter watch to check any speed, not just 60mph. Also as my 22 year old MK1 Golf is very accurate, it still astounds me that Audi are getting away with such inacurate speedos - after all, it can sing, dance, spot rain on the screen, put the lights on automatically, tell you when next to go to the dealer and be ripped off for a simple oil change, but can't get within 7 mph of the correct speed?????????? Link to comment Share on other sites More sharing options...
scooby_simon Posted January 31, 2005 Report Share Posted January 31, 2005 [ QUOTE ] The final drive for the 6 speed box in top gear (both for my A3 and Passat) gives as near as damn it 70mph at 2100rpm, so anyone else with the same box can quickly reference it. [/ QUOTE ] Assuming they are using the same wheels and tyres ! Link to comment Share on other sites More sharing options...
CarMad Posted February 1, 2005 Report Share Posted February 1, 2005 I also get about 10% out as all others do. I think the law states that it should always read over, NEVER under and should be quite accurate at 30mph. Well thats what I read a good while ago. I often set my speed on motorway road works to dead on 50mph and watch people brake hard in the slower lanes as I keep a constant speed with the cruise on. Cruising at a constant 85 is a GPS 78, within tolerance of Polices 10% + 2mph rule. Link to comment Share on other sites More sharing options...
RobK Posted February 1, 2005 Report Share Posted February 1, 2005 I posted about this a while ago. It's annoying because you end up looking at the speedo and trying to work out how fast you're really going. So on the motorway I'm thinking "The cops won't stop me for doing 85, so I want the speedo to be showing 95" and so on. The only alternative is to have the GPS on all the time! Link to comment Share on other sites More sharing options...
Rich Posted February 1, 2005 Report Share Posted February 1, 2005 This is the same on my little Focus too! Its about 5-8 mph out on the motorways....depending exactly how fast I'm going! I'm not sure I completely trust the gps speed though........ Link to comment Share on other sites More sharing options...
Tomk Posted February 1, 2005 Report Share Posted February 1, 2005 can we have a pole or something ? do people trust the GPS or the speedo as right ? Link to comment Share on other sites More sharing options...
Rich Posted February 1, 2005 Report Share Posted February 1, 2005 [ QUOTE ] can we have a pole or something ? do people trust the GPS or the speedo as right ? [/ QUOTE ] Personally not 100%. How can you when every now and then it plots you on the wrong road, or as your approaching your next direction command you see its 1 mile away, then suddenly jumps to being a lot closer because of gps delay. I agree the speedo probably has some tolerance, but I'd rather trust that....besides, the police won't care if you said your gps said you were under the speed limit! Rich Link to comment Share on other sites More sharing options...
Scotty Posted February 1, 2005 Report Share Posted February 1, 2005 I only trust the GPS when I have cruise control on and am maintaining a constanct speed. Link to comment Share on other sites More sharing options...
njc021073 Posted February 2, 2005 Author Report Share Posted February 2, 2005 I think I mentioned in an earlier post that I checked the speedo against KM marker posts on the motorway (basically you will see lots of white posts on the edge of most English motorways marking out every 100m)against my chronographs Tachymeter, and the GPS was spot on (at a steady speed set on cruise control) the speedo was well out! I have done the same on my two other cars (VWs) and they are also slightly out, but by a lot less. All this time I have been sticking to speed limits in roadworks, and getting annoyed with people for tailgating, and now I realise it is them that would like to stick to the upper limit, and me that is holding them up. Pretty embarrasing in a 6 month old Audi! Link to comment Share on other sites More sharing options...
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