i should mention that whilst the speedo says im doing 74 i am infact doing 68. they forgot to check before they put it at 74 i suppose.
All speedometers are set to read up to 10% above the true speed you are doing, this is done for a few reasons.
1) You think you are going faster in your shiny new car, than you are, thus you gain a slightly better impression of the car, the makers like this.......
2) It keeps all traffic speed down by up to 10%, good for safety.
3) Manufacturers do not want to be sued by thousands of drivers, who collect speeding tickets, due to the speedometer saying you were going slower than you actually were.