And then once you build the motor, you then have to build a controller for it, and that will probably be even harder and more expensive than the motor to design and construct.
You would probably be better off to find a wrecked EV of similar capabilities to what you want your car to do, and use it's drivetrain to run your car from.
If there are no such things in your area, you may be able to find a used brushed golfcart motor or similar, and it's controller; there are dozens of conversions of cars and ohter vehicles on http://diyelectriccar.com forums like that.