Vehicles mines are available in the following cities:
The losing vehicle of any battle may become disabled. If so, it will immediately change to an unaggressive stance against all vehicle rarities. It will carry on through the rest of the route normally but upon arrival, either the vehicle, an installed mod, or a weapon will be damaged at random. Also, any installed mods/weapons will be uninstalled. Damaged things require repair at a factory to become usable again. Yellow and green things are not repairable if damaged and are lost altogether, blue+ things must be repaired in a factory.
The attributes of a vehicle are different to those of a Ship
- Speed - How fast a vehicle travels, in km/h
- Attack - The base attack stat of the vehicle
- Armor - The base health like stat of the vehicle
- Capacity - How many items a vehicle can hold
- Dodge - The ability to lower an aggressor's offense or defender's defense
- Offense - The total offensive strength of carried weapons
- Defense - The total defensive strength of carried weapons
Attack, armor and dodge can be modified by attaching Mods to a vehicle, while offense and defense can be modified by attaching Weapons to the vehicle.These take up a portion of the vehicle's capacity.
This chart lists all known vehicles in the game with brief comments about their usefulness. Organized by speed. Updated last on 7/22/2013.
Another guide by Bob1234567890X is here: 
- Graphs removed, no longer accurate
Analysis By Color
Because the yellow vehicles are treated differently from green+ vehicles, here is a brief analysis of the yellow vehicles with their uses
Speed: 25 Capacity: 5 Attack: 0.2 Armor: 4
Trader - The Rickshaw has a median capacity (donkey is best at 7, unicycle worst at 1). It is the fastest yellow vehicle. This makes it unparalleled as the choice for yellow traders of moderate volume because the speed means you will generally outrun highwaymen and quickly move between cities. The attack and defense are mostly ignorable - nothing but other turboed rickshaws can hit a turboed rickshaw.
Highwayman - Of course, Rickshaws make the best choice for yellow highwaymen as well. Without a Rickshaw, Highwaymen will be constantly outrun by yellow traders Rickshaws. The capacity offers enough slots for a weapon or two as well as a little extra for spoils, and the inherent attack is better than the inherent armor, making it in the Highwayman's favor when fighting Rickshaw-to-Rickshaw.
Speed: 23 Capacity: 1 Attack: 1.6 Armor: 8
Trader - The Unicycle makes a very poor trading vehicle - the single capacity means you'll need 5 times as many unicycles as rickshaws to have the same capacity, and you'll still travel slowly. This is not a trading vehicle, as it's higher armor/attack is not worth losing four capacity.
Highwayman - The Unicycle's only benefit is its high attack. At 1.6 is is very difficult for a rickshaw to carry enough to adequately defend (Rickshaw base defense of 1, plus 4 slots for yellow weapons = 5 total defense with no cargo). Of course, that point is moot because even with a turbo engine a unicycle can't catch a rickshaw. That means unicycles are only good for attacking camels and donkeys. The higher speed means they will have an easy time catching them, but it will take 8 unicycles to empty one camel.
In short, get a Rickshaw.
Speed:21 Capacity:3 Attack:0 Armor:25
It's high armor can make it useful for gaurds. Load up on offense/attack and fight to damage, as you won't have capacity to steal things (back).
Speed: 19 Capacity: 4 Attack: 0.7 Armor: 6
Trader - Camels are both slower and have a lower capacity than the rickshaw. Despite the higher attack and armor, you'd need more of them and wait longer for travel with camels. Consider rickshaws instead as they and are far less susceptible to attack and will get your goods there sooner.
Highwayman - Same goes for highwayman with camels, upgrade to rickshaws. The only thing a camel can catch is camels and donkeys, and with only 4 slots, you can't take much of the spoils with you.
Speed: 15 Capacity: 7 Attack/Defense: 0
Donkeys are inferior to camels in every way except the higher capacity, but you could send a rickshaw there and back in less time than it takes to send a donkey there. So just go with the rickshaw.
- Go the fast route. Use rickshaws with two/three defensive weapons. You will outrun anything but another rickshaw. With two/three defensive weapons you'll beat anything but another rickshaw with more or equal weapons
- You could go the slow route, as speed isn't a factor in your profession.
- Again, use a rickshaw. Any slower vehicle will miss out on traders who are smart enough to use a rickshaw. Load up two weapons - this will give you good odds to beat any traders, even odds against any guards, and enough space to get something out of it
For more information the Yellow Vehicle Combat Guide goes into a lot of detail about the game mechanics and how to successfuly trade, guard or HM with yellow vehicles.
The problem with green vehicles is that they are treated as being in the same category as blue vehicles but they aren't repairable. That means that you can get attacked by far superior vehicles and if they damage you your vehicle is gone. On the flip side, since you can usually get them for very cheap losing them is not very costly.
Trader - Highest speed of any green makes it a shoe-in for traders. The speed actually puts it 9/23 in terms of speed, and ahead all blue vehicles in speed except the Roadster. The zero armor suggests making it part of large, cheap bubbles. Unfortunately, the capacity is quite low, tied for 3rd worst with the Donkey, so you'll need a lot.
Highwayman - It's fast, as mentioned above. This makes it decent for countering bubbles (The cheapness helps here too). It's attack is quite average, and the low capacity means you won't be using a lot of weapons and getting many spoils. It's basic Attack+Armor rating is in the bottom third. Basically, not that useful
Guards - Speed is always handy, but the low combined Attack+Armor and capacity makes it a poor choice for a guard
|Vehicle||Color||Speed||Capacity||Attack||Armor||Attack + Armor||Remarks|
|Sports Car||Blue||65||10||0.4||49||49.4||Only available on Aso(so not a problem on the other servers), and there is a very limited supply. Fastest vehicle possible for it's tier though.|
See the page for each server