A friend's father has the 3.0 diesel X5 and tows a large glazier's trailer throughout the south island of NZ. This is usually laden with glass and aggregate weight is approx. 3.5 metric tonnes. He claims it's the best towing vehicle he's owned and it's recently turned over 350,000 kms. For those that don't know, the south island of NZ is very mountainous (think Rockies).