Speedometer Accuracy!!

[Kev]

As some of you know I have recently bought a Road Angel which displays your speed and this is aclaimed to be "highly Accurate".

I can't believe how far out the speedometer is from the actual speed inicated by the RA. Its exactly 10% low through-out the range. An indicated 70mph displays 63mph on the odometer so I have been flying around for ages doing a paranoid 80mph when I have only been doing 72mph.

I since have been going through speed cameras doing an indicated 80mph and had no problems.

ps I am on the standard 17" wheels.

(edited, also proved on a Origin GPS)

[essexscooby]

I since have been going through speed cameras doing an indicated 80mph and had no problems.


I do hope your not condoning this to everyone Kev :wink:

[Kev]

Of course not. This is all IMHO. Don't come running to me if you get the dreaded FLASH FLASH. :shock: :roll:

[Viv]

Of course not. This is all IMHO. Don't come running to me if you get the dreaded FLASH FLASH. :shock: :roll:

"Well, officer, it was Kev wot made me done it!"

[Dave]

I can't belive its that far out.
The impreza can't be that bad. I have played with other cars at certain speeds and when we stoped we all had the same reading. One speed was being read through an Apexi commander thing to.

[Viv]

It's illegal to have the speedo under-read so most manufacturers make 'em over-read by a 5 to 10% margin. I think factors like tyre wear, overinflation and temperature have to be accounted for as well.
Dunno what margin the Impreza is supposed to be, but I read about one manufacturer recalling cars because the speedos were too acccurate!

[benm]

kev, glad your happy with the RA 8) i have noticed the same thing in my p1 about speed diferences. i think it is actually illegal to drive at less than the posted limit unless the road conditions deem it nessecary(highway code rule i seem to remember from driving lessons). so does this mean that we are all braking the law :?:

[Viv]

i think it is actually illegal to drive at less than the posted limit unless the road conditions deem it nessecary(highway code rule i seem to remember from driving lessons).

Perhaps they should put that in the highway code :lol:

[Abbylad]

think its illegal to drive 'a fair bit' under the speed limit, like 30 in a 60 or 40 in a 70, coz you`d be causing an obstruction or something like that

[mcgary]

I noticed this also in my mates audi s4 that his speedo is about 8mph out with road angel readings.

[benm]

its true i tell you :!: you can legally ram anyone out the way that is holding you up :lol: 8) :lol:

i am not a solicitor, nor do i have any legal qualifictions. and I'M NOT A BLOODY WINDOW CLEANER :wink:

[essexscooby]

i am not a solicitor, nor do i have any legal qualifictions. and I'M NOT A BLOODY WINDOW CLEANER :wink:

errrrrr my moneys on number 3 :wink:

[Kev]

Is it true all window cleaners are good whistlers. :lol:

[benm]

i got a little look at your avatar new kev.

and i mean a LITTLE look :lol: :lol:

[Kev]

:shock: :lol: :lol: 8) :wink:

[essexscooby]

:-.

[benm]

hairdressers don't whistle. they talk crap about where your going on holiday this year :lol: :lol:

[essexscooby]

I dont bother with you as its always "grays beach again" :roll: :lol:

[Dogus]

Meanwhile, back at the spedo accuracy debate.........

Totally agree with Kev's findings. I also have a Road Angel and theres a 10% difference throughout the range. I'm assuming the RA is the accurate one.

[Dave]

Just get a friend to follow you at a certain speed and then you can see what each cars speedo says and what the road angel has to say.

[benm]

i had my 18's fitted earlier and noticed my speedo is closer to what the RA say's. previously when at 110 the RA said 102/103. now it says 107/108. it looks like the 17's confuse the speedo :?

[Mickle]

think its illegal to drive 'a fair bit' under the speed limit, like 30 in a 60 or 40 in a 70, coz you`d be causing an obstruction or something like that

What if you're in a tractor or you are an OAP :D

You can't go faster than 40mph! :lol:

I was of the belief that the speed limit is just a suggested limit and you can go anything under that.

[jag]

no mike, abbylad is right on this one. tractor etc (Articulate - sp) vehicles go so slow on public roads cos they have the organge flashy lights. (and cos they cant reach high speeds)

i think under 50 in a normal car with free flowing traffic, is indeed an offence as you are technically more of a driving hazard... 20mph difference in speed is a lot. thats like goin 10mph all the way to work whilst everyone around you is doin 30. not a good idea, and you can get pulled over for it if you dont have "flashy" orange lights (hazards or whatever)

[Mickle]

cheers for that jag - I've learnt something new today :D

[jag]

i only know thiscos i nearly failed my driving tdest for "driving too slow" on one road. i thought i was playing safe by keepeing under the limit, but i was told after that if the conditions permit, you "should do the limit"...

i evidently have exceeded this advice and got pulled over anyways :roll: c'mon 2nd April, i want my licence back!

[essexscooby]

c'mon 2nd April, i want my licence back!

blimey thats come round quick! :shock:

[jag]

:D thats my appeal date, not when i get my licence back normally. dont worry keith, you havent lost another 6months of your life JUST yet

[essexscooby]

i was more concerned that I cant do the "DING DING" joke anymore :? :( :lol: :lol: :lol: :lol:

[jag]

lol, you cant anyways, cos im using taxis now ;) quicker when i need to get places. and cheap(ish) too.

[Simon1688]

i had my 18's fitted earlier and noticed my speedo is closer to what the RA say's. previously when at 110 the RA said 102/103. now it says 107/108. it looks like the 17's confuse the speedo :?

putting 18's apparently makes the car run faster according to the Miata Tire Size Calculator i dunno whether this has anything to do with this

[benm]

could well do. it looks like the've fitted the wrong size tyres on my 18's aswell :roll:

[jag]

if the P1 was designed to run on 18's as supposed to 17's, maybe the speedo calibration is set for the larger size wheels, making it read wrong on 17s?