No, not at all. For a normal GPS tracking application with the entire fleet automation features, a 2G enabled sim card is more than enough.
A postpaid M2M 2G SIM with data package of 50 MB and SMS facility is best recommended for the GPS tracking devices which use AVLView GPS tracking application. For establishing a one/two-way communication facility with your vehicle, a 2G SIM card must be fine. However for extended quality, you may use 3g sim cards, but expenses will be higher.
The machine to machine (M2M) 2G SIM cards are cost effective & ideal for GPS vehicle tracking, so you would be spending less on your bills. If you wish to have live video feeds to be sent from your vehicle, you are then required to go for a 3G/4G SIM.
Note: Administrations across the globe are in the process of switching over mobile data services from 2G to 3G/4G which may result in lowered 3G/4G costs soon, not guaranteed though.