I just checked the speedo on my '40 Chevy and it is off by 5 mph.The Police set up a speed warning contraption on Sawyer road and I saw that I was going 5 mph faster than the speedo said. The Hyundai is right on the money.

Years ago I had a '56 Chevy and for some reason, I put oversize tires on it. That threw the speedo off by 10 mph. I warned my wife to watch it, but did she listen? Do pigs fly?
Well, you guessed it, she got a ticket for speeding. We took the car to have the speedo calibrated and sure enough it was off by 10 mph.She got off by submitting the report and she only paid court costs.