What a smart key does that a remote head key cannot
A remote head key goes into the ignition and turns, and a coil around the cylinder reads its chip. A smart key never leaves your pocket. Antennas in the doors, the cabin and the trunk send out a low-frequency signal, the fob answers by radio, and the car unlocks when you touch the handle and starts when you press the button with the brake pedal down.
Because the car is always listening for it, a smart key asks more of the programming. The car has to accept it for starting the engine and for opening the doors, and on some cars it also carries its own seat and mirror memory settings.
The emergency blade, and why it still gets cut
Slide the release on the fob and a small key comes out. It opens the driver door when the fob battery or the car battery is dead, and on many cars the lock cylinder hides under a plastic cap on the handle that the blade pries off. A new fob ships with that blade uncut, so it gets cut to your lock by code before we leave.
A dead fob can usually still start the car. On Toyota and Honda, touch the fob to the start button and press it; many Chevrolet models have a backup pocket in the console or a cupholder instead. Your owner's manual names the spot.
Toyota and Lexus: the built-in security wait
Toyota and Lexus build a timer into smart key programming. On many models, part of the procedure is a wait of roughly 16 minutes before the car accepts a new fob. More recent models use a newer encrypted key, and adding one can mean that wait or an online step, depending on the car. Either way the visit runs longer and the quoted price stays where it was.
How a dealer builds a smart key bill
A dealer smart key is two lines. The parts counter sells the fob, and the service department bills programming as labor, typically $100 to $180, with the car in their bay. Lose the last fob and a tow gets added, $125 to $200, plus one to three days if the part is back-ordered.
By make, the gap is plain: Honda from $239 against about $480, Nissan from $249 against about $520, Lexus from $289 against about $580, and BMW (2010 to 2018) from $399 against about $750. If you already hold a dealer quote, the dealer quote page is where to send it.