I do check my car every couple of weeks. I have a routine that takes about 3 minutes total. About twice a month so about 24 times 3 minutes ~ 1 hour per year.

Although I could argue it actually takes zero time because I usually do this while waiting for somebody else to get into the car.

As a side note, if you are too busy to brush your teeth you should consider talking to a health professional about consequences of not brushing teeth. Or maybe your wife/girlfriend.