The mobility part of the pip award is used for the car, the care component does not come into it.
You find a car with a deposit you can afford to pay and the mobility part of the pip goes to motability. Most of the cars say TA beside them which means total allowance. Their are some cars that are slightly cheaper than the TA.
For the £303 every 4 weeks you get a car which is insured, taxed, serviced, new tyres when needed you just add the fuel.