If you don't have an air compressor in your garage you may want to drop by your local camera or computer store and pick up a can of compressed air. These are normally used for cleaning camera lenses or computer parts, but come in equally handy around a garage.
They are really valuable if you are changing the spark plugs on you BMW. As you probably already know, the plugs are recessed into deep holes in the BMW head, a great place for sand, grit, and other small items to gather. When you change your plugs you should always blow out these "holes" with air prior to removing the plugs. This will keep any of this foreign matter from falling into the combustion chamber and doing possible damage.
reprinted in Rio Grande, "Redline" Jan-Mar 96