[OT-ish] Optional Extras.

Please excuse me if you consider this to be off-topic, but this is the best place I can think of to ask the (slightly long-winded) question. Imagine you have a car database (MySQL driven). Different models have different optional extras (air-con, central locking, immobiliser etc). I need to store the optional extras in a searchable form - i.e. the customer may have a wish-list of electric windows, aircon, and power steering. However the optional extras list is not and will not be finalised when the system goes live (probably will never be finalised!). Therefore I cannot do the quick-and-dirty hack of putting all the options as binary fields in my car database, so must come up with a more elegant solution. I've thought of storing e.g. 10 tuples car.option1->aircon code, car.option2->powersteering code. etc. and also going down the header-detail route. My current quandry is to which is going to be better for the search aspect, considering I'd also like to give them a "best fit" option. Would it be to create a cursor on my fixed criterion (price, age etc) and then iterate through each of those manually in my php script (see - it isn't entirely off topic ;0) ) counting the matches for that record in the optional-extra detail table? Or would it be to do a select where (optionalextra1=mychoice1 or optionalextra2 = mychoice1 ......) and (optionalextra2=mychoice2 or optionalextra2 = mychoice2...... ) and .... etc etc (yeuch!). I have a sneaking suspicion that there's a more elegant way than either of these, but can't think of it at the moment. If you come up with the solution there's a beer in it for you the next time you're in Paphos, Cyprus! Thanks in advance, Dave.