Hmmm,it might be a touch puny for what you want and their really noisy as well.
The main problem is the 50 litre tank,you could perhaps spray one side of a car before your looking for air again,but there's a way of expanding the tank using an old gas bottle which could solve your problems.
Good thing with a Clarke is if it's not up to the job you can just return it and get a refund or upgrade,not so easy on t'internet.