This. 4 months is nothing. if you didn't have a baloune brought over onto this lease, they should be good to take it back a few months early. Depending on what time of year, higher end brands even have promotions for this type of thing, so it wont even fall on dealer negotiation, they just want to make sure you take another car.
My buddy has a x3 2013 with relatively low mileage, in 6 months, he changed batteries, water pump (that was draining the batteries), now his engine is torn apart at the garage, he is fed up with this garbage. Shit can go bad with BMW real fast.