Beej

Yes there is, and as I think I wrote in an earlier post I used that chart when I was trying to measure the speedo error in my car - the chart backs up the error that I calculated/observed.

Very interesting also re the Brockway R920 read out! That pretty much confirms what I reckon which is that the speedo reads 4-5mph (7-8 km/h) fast deliberately.

As for forgetting about this and just "drive the car" - believe me I do It's just that here in Australia, we have really **** speed limits that are ruthlessly enforced via hundreds of fixed and mobile speed camera's all over the highways, and they are tuned to get you on a very thin margin. Plus radar detectors and laser jammers are illegal and carry HUGE fines/penalties if you are caught with one. So, I like to know exactly how fast I going on the highway so that a) I don't get booked all the time and b) get to where I am going as fast as I can legally get away with!

Cheers,

Beej