These are fine for cars. I can offer no guidance to how well they work. Even if they are slightly abrasive, I can't imagine running one even a month would trash a head. These cleaners typically run for 30-60 seconds each use.
I have used slightly abrasive material to deep clean a head with no issues. This sort of cleaning is only necessary with stubborn deposits. Otherwise, isopropyl alcohol and firm pressure with swabs is all that is necessary. Depending on the tape, this might be necessary after a couple of hours of use, or 10 times that. When I ran only Maxell or TDK tapes (needle drops), I would go many months without a cleaning, with no degradation of sound. Now that I run pre recorded tapes, I find cleaning needs to be more frequent.