Maybe they are locals. Having pics of them might be pretty helpful. :)
The locals are extremely helpful and will go out of their way to ensure that you are satisfied, well if they know you very well. Other instances of such helpfulness is when you encounter an accident (usually on a highway stretch).
From the account that you have given, I probably think they are the workers of the BMW owner. I have personally seen labourers been picked up in such a fashion, though not on a daily basis.