Apparently a defective timing belt tensioner is a fairly common problem with this model. Two visits to the feckless dealer service department failed to solve the problem. Both times, the mechanic insisted that I should be using a thinner oil—which, of course, didn't solve the problem. On my third visit, a factory rep happened to be at the dealership, and he agreed with me that the defective tensioner (which could ultimately damage the engine) was the problem. They promptly made the repair, under warranty. But unfortunately,they didn't give me the opportunity to have the timing belt replaced while they made the repair. The belt must be replaced periodically at considerable expense. Since the belt must be removed when the tensioner is replaced, they could have done that in the course of the repair. I would have gladly payed the extra price of a new belt if given the opportunity.

The good news is that this is absolutely the ONLY problem I've ever had over the seven years that I've owned this great car.