Hi azizi,
just came across your post, and realized no one replied you. You probably bought your car already right? Anyway for what its worth here's my 10 years of experience across the range of 320i, 325msport & X5.
320i E90, relatively stable car for 1st 5 - 6 years of ownership (depending on owner). Fuel consumption also reasonable (city drive).
Service costs of BMW depending on where you go, if outside of Auto Bavaria & Ingress, places like M1 and Optimum...around RM 400 - 700 per service using fully/semi synth oil.
After 5-6 year mark, prepare for problems like - transmission mechatronic issues i.e. usually with valves that cause the car to jerk when stopping. To change is around RM8k-9k. Of course parts that affect road handling will need changing to get the most of BMW experience - your control arms will need replacing and also suspension (if still ori) will need to be changed + tyres which are very important for a BMW. Other issues I had once I crossed the 6 year mark are water leaking at radiator & oil seal problems that cause black oil loss (need gasket change or a top overhaul). Also watch out for the battery, original type are expensive to change (approx RM700 - RM1k).
Buy BMW if you love the brand and car. If you are looking for economy car better stick to non German.