As we all know, this topic shouldn’t even be a thing with Unturned’s current vehicle physics overtaking Assetto Corsa with ease, but I’ll just write it anyway.
Before starting, I’d like to point out that the quality of each mechanic would vary from car to car not just by rarity but also by its purpose. For example, the 3.0 F1 car might not be more rare than the tank, but that doesn’t mean its handling should be worse.
A good car shouldn’t just be able to go fast. If it does, then braking quickly is also a must.
The better the car, the shorter it travels when the brakes are hit, and the quicker the speed descends.
Varied Wheel Traction
Front, Rear and All Wheel Drive.
FWD is used in cheaper cars, and despite being better than RWD in slippery surfaces such as snow and wet tarmac, it suffers from understeer and worse traction in the dry ground.
RWD is used in mid-range cars, and excels in dry terrain. The downside of it is oversteer that might cause drifting (involuntary or not, hehe).
With too much power, it might also do wheelies when accelerating from zero.
AWD is used in vehicles with either high performance or focus on grip on slippery ground.
It’s especially balanced, since power is delivered to the four wheels. However, this is a system that adds significant weight to the car. Moreover, its more difficult to avoid a spinout in oversteer situations, so is to avoid added understeer at high speeds.
High Speed Understeer
You’ve probably played any racing game and realised going through corners at the same speed you’d drive in straight lines most likely ended up with you crashed on the outer barrier. This should happen in Unturned as well. A car going 100kph should have a smaller turning angle than one at half the velocity.
Suspension and Body Roll
The addition of suspension should have the most focus, since it’s what would make offroading controllable.
Suspension in different cars should vary by stiffness.
Softer suspension is present in the lower-end and in offroad vehicles. The softer the spings, the less bumps are noticed, but when steering, the car is more prone to body roll, which might lift one side of the car, or roll it over in the absolute worst case.
Stiffer suspension goes in higher performance cars. The stiffer it is, the less body roll occurs, but the more bumps are noticed, which affect speed depending on their height.