Charles aka Charlie

Has anybody else noticed how the actual speed on GPS is approx 5mph lower than the car speedo (especially at Motorway speeds).

Not just the Impreza, but every car I've tried Tom Tom in (and that's quite a few).

This can't be the speedo inaccuracy can it

Cheers,


Charlie

dharbige

Car speedos are allowed to over-read by 10% (i.e. they can show you as going 10% faster than you actually are), but cannot under-read at all.
It would therefore be logical for car manufacturers to aim for a 5% over-read.

Or 5mph at 100mph

TopBanana

Well Charles (can I call you Charlie?)... GPS speed is as accurate as you're going to get, just as long as you're not accelerating

gaz-cole

found mine to read the same as the speedo

scooby-tc

iTrader: (2)

mine reads lower but not by that much i dont think.iirc when im doing a steady 50 (speedo speed) the tomtom gps reads 46 which i think is about right

Marin

iTrader: (1)

My Navman is about 4mph slower than the car speedo - just put it down to speedo error.

dsmith

Mine's shocking. Gets close to the 10% error at times.

For years I've been thinking I'm going round @ 90 and then I found I was only a smidge over 80

ricardo_wrx

Yep its scary.... Tom Tom is more accurate than a £20k car! lol

One thing that is worth trying..... I have seen my brother do this on a video.
Next time your going on your hols on a plane. Take your Tom Tom and switch it on during the flight........ VERY VERY funny!

I'll not ruin the suprise...... but if you do want to know the result, PM me

scooby-tc

iTrader: (2)

how would it work on a plane? surely there would have to be a bluetooth gps device either installed on the PDA or something in the plane?

fast bloke

Why would you need something installed on the plane?

ricardo_wrx

Tom Tom uses satalites. Bluetooth only connects it to the internet etc.

Luminous

iTrader: (3)

I want to know the result, chances of me having the device in the right place at the right time and remember is well....well I have more chance of going to the moon :A

scooby-tc

iTrader: (2)

You have to have a gps device connected to the tomtom device in order for it to work,only way is either a gps bluetooth receiver or a cable gps receiver without either of these the tomtom cant get a signal from the satellites surely?

fast bloke

A Tom Tom is a complete system. It has receivers built in

joey_turbo

iTrader: (26)

scooby_tc, you must be thinking of the Tom Tom software on a PDA or mobile phone, that requires a separate GPS device.
Don't think I'd be trying it this year, but it would be interesting to see the speeds on the plane

scooby-tc

iTrader: (2)

My PDA one doesnt,it comes with the software and a cable gps receiver.I guess the tomtom in question is like one of the tomtom Go systems? never had one of those which is why i was interested in how it works on a plane.Also why would anyone take a tomtom on a plane?

scooby-tc

iTrader: (2)

ahh just read the above.....all makes sense now

fast bloke

Find the way to the bogs maybe?

joey_turbo

iTrader: (26)

Tom Toms were standalone GPS Sat NAv systems before they brought the software out to use with PDA's. I just sold mine, I had a bluetooth device. Got a proper TomTom unit now. Much better.
I'd take one on plane if I was driving abroad and wanted to see the sights.

mart360

My tom tom (pda), consistantly gives my speed as 5mph below the speedo

going to try a stand alone until on weds, i,ll see how they differ


Mart

swampster

iTrader: (1)

Tom Tom or any other Sat nav still needs a line of site to two or more satellites, still would imagine it difficult to work even remotely on a plane unless you're holding it upto the window.

Off course it'd be ok I guess in the Window of something like a Cessna, apart from the fact it'd have a bit of a fit as far as altitude and relating it's position to the in built maps I guess.

pslewis

It's not scary that it is more accurate than a £5 speedo!!

Funnily enough, my Scooby holds much more petrol than a Tom Tom

ricardo_wrx

Ive had that many PM's I'll just post the result here. Sorry if its going to ruin the suprise, if you fancied trying it out.

Well you know the volume gets louder the faster you go...... imagine nearly 500mph! everyone on the plane heard!
But because the route kept changing off the roads (cross country) he couldnt switch it off because it was trying to re-calculate the route.

He did eventually get the mute working and videoed the map moving accross Sussex travelling at over 500mph, then it got very confused over the English channel.