Tardis is one of the most effective tar removers. Autosmart often only sells to companys that uses it and not for selling it. But do you get a nice sells person from the distributor you can make a deal with them as a private person. This is in Sweden how it works. And could be another story in the US.
We use very much of tar removers here. And then the offerings of them is quite large. During the winter it`s a maintance product even lol. Before foamcannons got really popular. The most common method of those that take care of their cars. Was to have 2 pump spray bottles. One with a tar remover which is not so potent as tardis but close to it. Spray the tar remover on dry paint as a first step. Don`t apply it over the side windows cause if you get in the doors it desolves the rust protection in them over time. So on the lower side panels and the back of the car and let it dwell for as long as possible before it dries. Then over the tar remover an alkaline based degreaser is sprayed over the whole car. Dwell for about 5 minutes and then PW clean rinsing it off from bottom and work your way up. This got you all the road salt and very much of the road grime and road film off the car. And then do your bucket wash as useally. You don`t get the rinse bucket that dirty and the last road film gets off with ease with a few wipes with the wash media. This is often done on the gas stations that have wash bay garages they lease out by the hour. And is done in the winter months when the road salt is on the roads. Just a little information on how many do it here