After your factory BMW warranty expires, you can always look to an after market extended warranty if you are afraid of expensive repairs.
I just bought a '99 328i and purchased a 4 year/ 48K mile warranty. I bought the extended warranty from the garage that services all our cars. I hope I never have to use this warranty but should I have to, I'll be covered. Interesting that if you are on a trip, this extended warrty will cover a small amount of hotel expenses.