[Oval_Overload]

No way in hell you're going to salvage a WarP series motor. My suggestion would be to steal one, whilst distracting the cashier with large sums of money.

As for voltage, the motors can be substantially over volted if adequate cooling is provided. Look for a Sep-Ex/Shunt wound motor if you can. With these, you can control the field coil separately from the from the armature, acting like a transmission. Turning the field current down gains you RPM at the expense of torque, like an overdrive gear.

In regards to vehicle range, that depends on the watt hour capacity of your traction pack. As a general rule of thumb, more voltage nets you more range and more speed. More coin nets you more voltage. My advice to you is to concentrate on three primary areas of your build and let the rest follow.

Motor
A used motor will work fine, but it has to be properly sized to the car and properly cooled. You state that you want to sustain 50 MPH. If you don't buy new motor, you'll probably have to find a used motor designed for use in an EV. Don't cheat yourself on power. You don't want to be that ass causing a traffic snarl at every stoplight.

12 VDC power supply
Sit on the floor pretzel style, close your eyes, and repeat after me... "Don't cheap out on the DC/DC... Don't cheap out on the DC/DC..." You can have the worlds best traction pack, but if your 12 VDC system conks out, you're hosed. Without 12 volts, you can't energize the contractors. Use a DC/DC converter, solar panels, whatever. just make sure it works.

Battery charger
It doesn't matter if you're running used UPS batteries or fancy lithium cells, a chincy charger is the quickest way to toast them.

~Jim