It's nice to know what role a vehicle is generally designed for when it's constructed, and while St. Louis Blues started on the subject, all the extra vehicles that are floating around now demand a revisit.
A vehicles classification is based on a couple of factors - engine size, crew, vehicle type and vehicle role. For example, V6 Interceptor Gunship, V12 multi-crew Rollcage Tank.
Not all vehicles will include all the factors - see below for exceptions.
This is simply the V rating of the engine, V6, V8 or V12.
A vehicle is assumed to have a crew of one, but if it's designed to carry more, add the notation 'multi-crew' to the classification. Whilst it's more accurate to add 'Single person' to a vehicles classification if it only contains one occupant, it is generally ignored.
Again, self-explanatory, this is body type of the vehicle, such as Interceptor, Renegade, Civilian or whatever. If a vehicle is stripped, list that here as well.
The role is what the vehicle was designed for. The following list is not exhaustive but does cover most of the general roles. There are no strict guidelines for what vehicle fits into what sort of role - all designers have differing ideas of what a 'tank' is for example - and as such, there is a lot of space for confusion.
Carrier: A carrier is designed to transport cargo or passengers, and while they have usually have combat capabilities; it is not their primary use.
Gunships: A gunship is a vehicle that carries the maximum amount of weapons to deliver the maximum damage. Firepower is the keyword here.
Multi-Role: A multi-role vehicle tries to be a blend of all things, carrying firepower, armour and still having enough speed to be useful. These vehicles are the jack-of-all-trades, designed to be flexible enough to react in all situations.
Performance: Like its namesake, the performance vehicle is designed for speed and handling. They are usually light and fast with weaponry up front.
Tank: A tank is built to soak up damage rather than take it. They are usually the slowest of the vehicle types used when something needs protecting or as bait in ambushes.
Bikes are classified into two types, ignoring engine size. A bike or trike is broken down into two classifications.
Road Bike: A road bike is generally light, fast and lightly armed, being primarily designed for scouting and as couriers.
Heavy Bike: A heavy bike is larger and slower then the road bike, but in turn, it carries a lot more firepower - sometimes enough to stand up to a heavier vehicle.
With the exception of engine types, jetcopters follow all normal classification types - Gunships, Multi-Role and Transports are the most common roles for jetcopters.
Classifications for the big rigs are pretty irrelevant - almost all them fall into the Gunship, Tank and Transport classifications, and most of them carry additional crewman as well. As such simply list the vehicle type when classifying these.