Originally Posted by tylerk
I'm looking for a kit that includes motors, sensors, and all of the mechanical parts for an RC car. I would then take care of the power supply, electrically controlling the motors, receiving and interpreting the RC signal, etc.
That includes just about any r/c car kit you can buy, none of them come with any electronics in them. For something simple and easy to build I would choose the Tamiya TT-01 chassis, available with many body styles. It will also include a basic drive motor.
Although if you have no idea of how r/c cars normally work, I would suggest you get a full package including radio, there are ready to run cars that can be bought for less than just buying an empty chassis. You can then see what you are trying to replicate, such as the fully proportional steering and speed control, and the speed that they react to inputs. These systems have had 40 years of development behind them so have been refined as much as possible.