AUS 2013 86 GTS Speedo Inaccurate
 

hi all,

ive got an 2013 86 gts in aus w the digital speedo.

for a while i have thought the speedo is incorrect, so today i did a test with a gps speed tester.

EDITED (i had them around the wrong way)
when i do 100kmh on the speedo, the GPS shows 96kmh.
when i do 60kmh on the speedo, the GPS shows 56kmh.

seems its about 4kmh out.

the speed needle on the dash matches the digital dash readout speed.

anyone else noticed this with their car?

anyone know how to calibrate the speedo?

thanks, pop.

This is normal. If you look at car specs you'll see there's a figure for "speed when 100kph indicated" or similar. All cars are designed to be slightly slower than indicated, usually about 3%. If you really want to fix it, you can get diferent tires that have a slightly different overall diameter. Also the GPS unit is likely not strictly 100% accurate either, there are tolerances there too.

Switch over to mph and difference will be smaller ^^

aftermarket tires or oem?

Tire size could affect it too.

thanks for the replies guys.

yes i thought of tyres. would love a hack to remove the intentional incorrect reporting of speed. guess ill just have to "add four" to know my real speed.

thanks, pops

It should change proportionally ie, If it reads 100 and your doing 96 at a 50 reading you should be doing 48. It`s just how it works and is normal operation.

I'm in Australia and get the same speedo error vs GPS in every car I've driven, our 86, Tucson, Cruze, Aurion, Camry, Commodore, RAV4 the list goes on and on. completely normal and nothing to be concerned about.

Seems backwards. The manufacturers do not want to be liable for you going over the speed limit. When stock tires are new tires, the speedometer should read 2-3% higher than actual. When I put new 225/45R17 tires on my car, the speedo was then pretty accurate at 60mph

You're right, it should be the other way around. OP has not confirmed wheel/tire size, if he has bigger diameter tires vs stock that would cause his issue of car speedo being lower than gps speedo.

tyres are pilot spot 4's, 215/45 ZR17, about 6 months old.

you're right, i typed it out incorrectly. i have corrected the original post. thx.

thats also what i was expecting, but not what was shown on the gps. i tested on long stretches of 100 and 60 -- and it was 4kmh out both times, weird right.