That sucks.
Did you have a low coolant warning on the dash prior to overheating? One common issue I've seen online is that the earlier M240i's didn't come with the rock guard from the factory. So it's prone to getting punctured/damaged from debris on the road if you're going fast and/or vehicles in front kick something up = coolant leak.
https://www.2addicts.com/forums/show...2F2500%20miles.
The next most common issue would be the radiator fan, followed by the water pump.