What's more accurate? Speedo or GPS?

[dannyboi]

I think Jarryd is right about the 5%. My GPS registers about 105 kph when the speedo shows 110 kph. It's pretty good if you take into account how the cruise control system will generally go up when you're going downhill.

[lmat]

my Garmin GPS reads about 106 when spedo is on 100 in my 2008es lancer and in the wifes 2011 RA reads almost the same just a slight fluctuation between 105 and 106 when indicated speed is 100 (different size tyres maybe) however if i take the same Garmin GPS and put in my 2004 SV6 commodore the GPS and the analogue needle as well as the digital speedometer ALL read 100. This suggest to me that both of our lancers are inaccurate as on the hwy cars seem to pass regularly but in the commodore you often seem to catch other cars.

[tnode]

The Hilux I drive for work says 108 on the GPS when the speedo says 130, I passed two radar gun cops that day, one bike one car, and neither followed.

It's not that far out at 60 but people fly past me if I do 110 on the freeway.

[Mez]

Same result here.
On the freeway doing 100kph (lancer speedo) my Garmin says i'm doing about 95 kph. Makes me feel kinda slower than what I should be on these roads