And now youve got it, thats why he needs more pulses thats why the car companies did it, and he needs more than one per DS rev. It just isn't going to give the resolution you want, how often will he be able to update the speedo with a counter timer setup he will still need to count for over one second to get 2.28 pulses and at two second you have 4.56 so the speeso will jump from 5 kph to 10 kph with nothing in between.