This is going to be more of a mechanical issue than an electrical one. It definitely CAN be done. http://falconlabs.com/ELECCAR/eleccar.htm This car uses one DC motor direct drive to the rear axle (no transmission). it is a bit sluggish starting from zero speed, but is drivable in flat country and cruises well on the freeway. A higher capacity controller would solve all sluggish starting problems, at the expense of shorter cruising range in proportion to the extra amps you use each time you start.
The real problem with direct drive is mounting and connecting the motors. You might look for a vehicle with IRS and 'halfshafts'. Jaguar XK and Datsun 510 sedan are two cars that come to mind. In these cars there is not a solid differential that is a key part of the suspension. Instead the differential sits in the middle and is connected to the wheels by the 'half-shafts'. remove the differential, connect motors the same place as the half shafts went, and you have two motors independently driving the two back wheels. This will be a MAJOR mechanical undertaking -- at least as complex as building your own motor-to-transmission adaptor plate -- and should not be considered unless you have good machine shop and steel fabrication facilities backing you up, but it definitely can be done.
There is a Black and Decker DC motor which is popular in electrathon projects that has a nice configuration (large diameter for torque and short to fit two of them back to back), but I am not sure if they would be strong enough for a full size car, or if they are even available. I think it is called Etek .... Here is a link to information - you will need to look carefully to see if this motor meets your requirements. http://www.thunderstruck-ev.com/etek-r.htm
And one more comment -- be sure to look at motor speed -- if you are direct driving the wheels your motor needs to turn more slowly than it would if you are going to use the transmission and/or differential like in a normal car. Make sure you have enough torque for a decent start and then enough maximum RPM to give you the top speed you want.
