Application is the key word above. Many low dollar and a few high dollar conversions of been done with DC motors. Usually, a DC motor is less expensive than an AC motor. Drag race only cars benefit from the awesome low-end torque found with DC motors, some even run multiple motors, however DC motors are usually considered rpm limited and not capable of hitting high track speed. This can be overcome with an overdrive or two from someone like Gear Vendors.
Note: all OE car manufacturers making electric vehicles today use high quality liquid cooled motors and inverters. Some motors come with a matched inverter/controller and others leave you to find your own compatible inverter.
Next you need to consider the quality and durability you are looking for. Are you just looking to drive very short distances so you can say "look Ma I made an electric car" or are you looking for OE quality, a vehicle you can drive anywhere, including highway driving and maybe even light towing or weight hauling applications. Suffice it to say there are many variables to choosing the correct motor and inverter for your needs. Learn from others that have gone before you and, in some cases, changed motors multiple times before finding the package that works for them. The next big decision will be are you building a low voltage or high voltage system. Many of the DIY level packages will be air cooled and run at lower voltages like 72v to 96v. Most OE quality conversions use high voltage (275 to 800v) and these are always liquid cooled. Typically, the higher the voltage, the fewer amps are required to do the same work. High voltage is usually more energy efficient.
Note: Every motor has a minimum and maximum voltage that the motor manufacturer recommends.
Torque Trends is an authorized distributor/installer of the UQM/Danfoss motor line. For most applications we recommend the PP-High Speed 160 kW liquid cooled motor which comes with a liquid cooled and matched inverter. For short range light duty DIY projects on a tight budget, we recommend the low voltage Net Gain Hyper-9 air cooled motor. TTI fits many motor packages with our TorqueBox brand reduction gearbox.