Apparantly the car itself is alright - looks like an MBX5T copy to me - which is no bad thing.
The ESC probably isn't quite up to the job. It's a Hobbywing 80A ESC capable of 4S max. If it were me, I'd put a Hobbywing 150A ESC in there instead, or better, a Mamba Monster Max, as that 80A will be overstressed.
Also, the motor is too short to use in a truggy without issues (it doesn't have enough torque). It is Feigao based - so it'll run hot anyway, but worse, it is a 36mm diameter can that is only 65mm long! You'd need at least a 70mm motor for a truggy. A 36-70 Medusa would be far better.
The kV is right for 4S though.
The motor just doesn't seem to have the torque required. When I did my first brushless conversion (on a Losi 8ight, with an MMM, a Medusa 36-60-2000 motor, and Flightpower 4S LiPOs) it could wheelie on tarmac easily, and was quick to boot. I came across one of the Caster RTR buggies, on 4S, with a 2000kV motor (the same as the truggy), and it could not even lift the front wheels on tarmac, and it was also slower.
In my opinion, I'd get the Caster Pro, pick up a good condition used MMM off RC-Tech, a Medusa if you can still get it, and do it properly with good LiPOs. It will initially cost more, but you will get more satisfaction that way.
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