Understanding your SMART FORTWO Cabrio (451) bulb sizes makes it easy to change the vehicle's appearance and brings instant performance or comfort benefits. Check out SMART FORTWO Cabrio (451) light bulb list to see precisely what kind of lamp you need and how much it will cost you to replace an old bulb. SMART FORTWO Cabrio (451) LED lights are the best and most energy-efficient lighting type, but they are also very pricey.