It is not hard if you just use the handling of any other similar Vehicle,
but It is not easy if you want a unique Handling,
so, here is the idea.
if you have created a car model which is present in our world
Then all you have to do is, search its info. on google!
if it is your own >Read Me first
you have to fill about 33 things for Handling,
some of them are easy,
IDE of vehicle, Tire, flag,
Some of them comes out when you Open your model in any modeling software!
Vehicle Dimensions, Centre Of Mass, etc.
Things like these are your choice or can be written by doing exp.
Number Of Gears,Damage Multiplier, Acceleration & top speed, etc
remaining like Mass & can be used from similar vehicles,