Did you honestly think it was that easy, driftfreak1212? Creating a car is an incredibly difficult task. I've tinkered with 3dsmax since 3D Studio Max 2.0 and I still couldn't model a car that's A) Beautiful enough to qualify for acceptable content and B) Isn't 1,000,000 polygons. People forget that not only do these modellers have to have the skills to create these cars on a computer screen, but they must do it efficiently or the car would take up way too much memory (RAM) and the game would run slowly.
Modelling is only part of the battle. Albeit, possibly the most difficult. Next, you have to create the physics and sounds for the car. Sure, you could do what many people do and re-use the physics and/or sounds from another established car. Maybe you just make some tweaks here or there to alter the physics, but if you want the car to behave like the real life version, you need to do research and testing. No two cars sound exactly the same, so while you can borrow the sounds from another Assetto Corsa car, the best Modders create their own sounds.
Basically, what I'm saying is... Creating a car is NEVER going to be a "push this button and you're done" exercise. Well, I shouldn't say "never". But, if it were that simple, you can bet money that the end result would be terrible quality.