Car Keypad

yes, that L1 looks good!

for C1 it should be a ultra low ESR electrolytic. Thats becouse they are like the "fastest" and you can get them with big F values.
elextrolytic is fine, as long as you dont take the super cheap ones.
my C1: http://shop.conrad.at/ce/de/product/445903/KONDENSATORULTRA-LOW-ESR220F35V
its rated with 6000h at 105°C, that should be enough...

in your chart you have a 220pF, what should be a 220µF :wink:
and with a 20V zener diode your still safe but it will not be so close to trigger unwanted (14,4V is quite common in a car)

thats how this looks in my prototype:

(my 1N is a little oversized, had no smaller around ::))