Does anyone know how to remove the yellowish stain left from the brake dust? Living in New England you don't get many chances to really wash the car well during the winter. Due to that the rims have become stained. I already tried using rim cleaner from the auto parts store with no luck.

Well the rims on the 740 do collect brake dust (though not as quickly as it sounds the newer volvos do). To clean them I use lots of elbow grease I am afraid. I have heard that keeping wax on the rims helps to clean them, and even going as far as wiping them with a clean cotton cloth a couple of times a wekk (not easy to do in the winter I agree, but you are supposed to switch to your steel rims and snow tires for the winter :) (though I know they don't look very nice, and you may be able to get by with all seasons in your area). Anyway I guess all I can suggest is when you do get them clean give them a coat of wax (the yellow colour may be rust from the metal particles in the brake dust that has attached itself to your rims) Don't use an acid based wheel cleaner (will eat the clearcoat and make your troubles worse) and clean the wheels as often as possible (go to a coin operated pressure wash and blast them in the winter if you have to). I know it doesn't help your current situation but hopefully it will help you in the long run.

What brand and type of cleaner did you use? Some cleaners themselves can stain the rims.