As you correctly surmised this is a torque problem.

I am going to assume that the center of mass of the car is at the midpoint of the axle and rear of the car. This assumption is clearly ridiculous, but I don't know that much about cars. Obviously the CM is going to be somewhere between the geometric center of the car and the front axle. But this is what I'm going to assume and you can adapt the problem accordingly.

I am going to assume that the car has been lifted to an angle

. Call the distance from the front axle to the rear of the car (where it's being lifted from) to be D. Take a counter-clockwise torque to be positive and take the axis of rotation to be about the front axle.. Then we have

Noting that

we get, upon solving for F:

.

What surprises me about this is that the applied force is constant. I would have guessed that it would depend on

.

-Dan