It's worth noting on this topic that if, like me, you have the Diamonbrite coating on your car, then they told me to NOT use any products to remove the Tar. I had bought the AutGlym stuff. I was told to use only the Diamonbrite conserver.
So be warned. Here's the email reply I got.
Dear Sir,
Please do not use any polish, wax or white sprit product on the Diamondbrite.
Try using the conserver neat, leaving on for about 15 minutes and then polish off. You may need to do this twice.
This should remove the tar markings.
Regards,
Rob Town
Customer Services