Given your history, I would strongly advise against ordering a car just because it has short lead times. Good things are often worth waiting for, and there are sometimes reasons why some cars can be obtained very quickly! I would concentrate your efforts on making sure that you order a car that is 100% right for you. As long as you have ordered, I’m sure that Motability won’t leave you in the lurch and without transport, especially as the reason for the change is due to a faulty car.