considering to buy 2001 BMW 525i at 85 K Mileage. Please let me know if this car requires 9ok Service done if so what is cost for the service and does it require to change the timing belt?

These cars run 'conditioned based service so you will need to check the service book for next due service. if just purchacing i would recommend an inspection 2, the major service, price is dependant on you repairer, so call locally and ask around. the BMW engine runs a cam chain and it is not something that requires replacement.

Probably the only major service item that I can think of would be the trans service. I own a 2001 530, with 100,500 miles on it. Runs Great! has been well maintained (I think!), has had a few minor things - like valve cover gasket leak, cracked valve cover, plugs, and both front hubs replaced -- the sort of thing that is not unexpected for a car with this mileage. We have taken care of those things, and other than tires and brakes, have not had to put alot of $$ into this vehicle. That's why I want to get the tranny service done - before anything bad happens. We plan to drive the wheels off this car, which as it looks now, is gonna be a long time.