Do you know any customer using service modules for car repairing?

I do not know of any customers who use Service for car repairs.
However, there are lots of companies that use Service (from Triton 2.2 to LN6.1) for all sorts of engine repairs in different types of equipment.
Therefore, I do not see any problems why Service cannot be used for car repair specifically.

main difference is B2B vs B2C. When you repair cars, your customers are individuals, not companies.

Even in a B2C environment you can utilize BAAN Service to repair cars.
It all depends how you set up the Service application.
BAAN Service is used by companies in a B2C environment and as far as I am concerned this can be from Triton 2.2 upto LN.