I don't think there is any reason to expect breakdowns. Heck, your car is hardly broken in yet. I have no hesitation to take any of my cars on a trip. Keep them in good repair and you should be fine. I don't think there is any way you're going to guess which part you're going to need. If you know something is going to give you trouble, then fix it before you go. Take your tools, your manuals, your cell phone, the Roadside assistance number and the number of some parts houses than can overnight something to you if needed. I have never had a breakdown of any significance.

Len
'99 E300TD 87,000 miles
'83 240D 345,000 miles original owner
'59 220S Cabriolet