Has anyone considered Dodo Juice Tarmalade?
It's not designed to be as effective, as quickly as Tardis, in fact, it's not really designed to compete with Tardis at all to be honest. It is a far nicer product to use, as it's not harsh at all and smells lovely, unlike tardis, which is quite the opposite.
It is also far better for removing isolated tar spots, which is what most passionate car owners, who care for their car, will come across as they tend to wash it regularly and use wax, which does definitely help to prevent the tar from sticking.