I would suggest calling a locksmith or trying to jimmy the lock with a clothes hanger.
Try jiggling the steering wheel a little, press your brake pedal, and make sure your car is in PARK.
Most people would look for them but if you cant find them then buy new ones.
go to your dealership and ask if it is possible to get new keys. sometimes there is a fee. Otherwise go crazy looking for them around your house etc.
Check the current specs for BMW and Mercedes wagons both have HIGH performance wagons and go back in forth between being the fastest. Actually the fastest station wagon is the new Audi RS6 hands...
on average probably around 3500 lbs.