Limits for FX Items on Vehicles

Just as characters are limited in their ability to carry magic items, a vehicle can only bear so many functional magic items. The limits are as follows:
1 ramplate or set of bumpers
1 steering wheel
1 coat of paint
1 set of tires
1 pair of headlights
1 horn or siren
1 containment area (ashtray, glove compartment, trunk, etc.)
1 non-electronic accessory (hung from the rear view mirror, on the dashboard, etc.)
1 seat or set of seats
1 engine or engine accessory
1 set of windows (including windshield and side windows)
2 electronic accessories (stereo, CB radio, car alarm, etc.)