I'm sorry life has brought you to this point. I'm sure 3 disposable barbecues should be more than enough, if the method is carried out correctly. After all, people have succeeded with far less than that. As long as you allow the smoke and flames to disappear before bringing your barbecues into the car, there shouldn't be any problems. Although like someone else has already said, it might be a good idea to place the barbecues on top of a shallow dish with water or at the very least, place them on top of some bricks so the upholstery doesn't get too hot. Charcoal is also my method of choice, but I haven't yet mustered the courage it takes to ctb. Do you have a date set for when you plan to go ahead?