On a recent trip I decided to see if I could check the accuracy of my S2000 speedometer with my handheld GPS (Garmin iQue). Setting it to the screen that shows top speed, average speed, distance travelled, etc. (after re-setting everything to 0) I took off down XX. I eased up on 60 mph and held it briefly then backed off. The GPS showed my max speed as 59.9. When I went up t 70, it showed 69.9. At 80 (you guessed it) I was really doing 79.9. Same ratio for 90. Interestingly enough, when my speedo showed 100, so did the GPS. Pretty accurate speedo - I was suprised.
Any handheld GPS that will give your speed should do the trick. Be careful and keep your eys on the road (and sky).

 

yeah it's pretty accurate. i checked to 70mph. but my gps monitor doesn't have decimals.

 

At 138 my GPS showed 132

 

I saw a 4mph (4%) error at 100 MPh vs. the GPS.

 

i love big digital readouts.. reminds me of granny alarm clocks

 

This is kind of a general interest topic and would be viewed more in S2000 Talk. Leaving a link in UTH.

 

My Mister2 is off by 5% in the wrong direction. I'm actually going 5% faster than what the speedo says according to my friend's GPS.

I haven't checked the S yet.

 

we have a cop radar van here which takes a photograph of your car when you go above the speed limit. I have to say the S speedo is dead on.

 

In MOTOR magazine's 2003 Performance Car of The Year test, the S2000's top speed before the braking area of the strip was 246km/h (153.75mph), and on the radar gun it read dead-on accurate, 246km/h...pretty cool.

 

Good info dude....