(1) isopropyl, 100% is best (not the drugstore 70% stuff). Use with a stiff brush. However, not 100% effective.
(2) some have said windex. Haven't tried this myself.
(3) automotive upholstery cleaner. The type intended for oil & grease.
(4) carburetor or brake cleaner. But they will smell while they evaporate and they are really strong solvents so be careful, especially with colored carpets.
(5) automotive bug & tar remover. Same like #4 above.
Carburetor cleaner probably the strongest... That stuff removes and dissolves almost everything if allowed to soak long enough. Back in the day when I used to wrench, I have seen mechanics spray that onto car seats & headliners where nasty grease stains were... The stuff INSTANTLY dissolved the stains and shop rags were used to soak up the solvent that disappeared into the upholstery. It's as if the stains were never there and the solvent dried very quickly. Can't say whether there were any long term detrimental side effects from their use though.