Good question. The 451 seems to be like the 450 with less features and more reliability.
Unlike the 450, the 451 doesn't have a switch in the cabin to open the boot.
It does have a switch built into the external boot lid handle but people prefer internal release buttons.
Of course. Smart didn't bother to fit it so it saved a tiny amount of money.
You only have to create a switch from what is already available and add a simple wire.
What we will be doing is tapping into the wire that runs between the SAM unit and the boot
release switch on the boot flap. So far I have identified 2 different wiring colours used.