My odometer is within 1% but my speedo is about 7% fast. I've tested it against both a GPS and one of those radar units they put along the highway to get you to slow down, and had the same results. My Mini Cooper is almost exactly the same.
British Engineering?

We all like to think of ourselves as rugged individualists. But when push comes to shove most of us are sheep who do what we are told. Worst of all, a lot of us become unpaid agents of whoever is controlling the agenda by enforcing the current dogma on the few rugged individualists who actually exist.