My E320 does not have a Vacuum guage or a mileage guage. OBDII only came out in 1996 for North American cars from what I have read. Part of the reason I bought the MPGuino kit was for interest and economy. I learnt much from building the kit supplied by Fundamental Logic. The theory behind the electronis board and the components are explained extermely well in lecture notes supplied by SparkFun Electronics - News