How long does a smart motor last?

Hello smart experts, yesterday I was a little proud of a friend, but also a little thoughtful about her new, used smart. It’s a petrol engine (I’m not a smart expert, maybe there are several gasoline engines) and despite its good condition she has some concerns now, because the car has already run over 40 tkm. She has heard – after the purchase – that the life of the engines should not be so high. Since she invested a considerable part of her savings in her car, she naturally wants to drive with it for a long time. What should she do, so that she can enjoy it for a long time? (normal maintenance according to the plan is logical, there are only “special measures” asked. How long do the smart petrolers live according to experience? Of course, the behavior of the drivers depends on the experience, but there should already be experiences. Thanks already for the info re