Amanda
We can't give detailed financial advice on the forum, you might want to get face to face advice from a trained advisor before proceeding.
In principle it should not be a problem, the difficulty is that it is potentially at the discretion on a DWP Decision Maker, the purchase should not be a problem, the difficulty may be down the lie if the pension temporarily appears in your account.
One way around this would be to have the money paid direct to the car dealership, if that is possible.
Failing that I would write to the DWP and explain what you are doing.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
