I can clean my car much better than the 50 cent vacuum cleaner machines at the gas station. In addition, I can work without time pressure.
If you extrapolate the whole and his car once a month "relaxed" sucks, I would pay a maximum of 12 EUR at the gas station in the year (assuming you throw two times 50 cent pure. Makes sense). Then, this "investment" amortized in 4 years.
Joking aside. It's just much more enjoyable it can make at home!