2007 BMW 525i - 75,000 miles
2008 GMC Acadia - 55,000 miles
2010 VW Jetta - 20,000 miles
We haven't done road trips in any of these cars, so 90% of the miles are from highway commutes.
We will trade in the BMW at 100,000 miles. The maintenance costs are just exorbitant, not to mention it takes a ridiculous amount of time to get parts shipped from Germany.
Not sure when we'll trade in the Acadia. We've had to replace the HID headlights three times now, and the seat belts were replaced because of a recall. The transmission is very slow to shift, both up and down, so I have a feeling that will go at some point in the next few years. We had a 1999 GMC Yukon before the Acadia, and it only underwent routine maintenance until we traded it in at 130,000 miles, so I'm not sure if it's just our individual vehicle that has problems or a bunch of them. The transmission is known to be slow, but I haven't heard of multiple headlight failures.
The Jetta has been an excellent commuter car. It's small enough to park in tight spaces, but large enough to fit four people comfortably. As long as nothing major happens, we plan on keeping it another 6-7 years.