These are not finished designs, just ideas. You need to test and if necessary adjust/adapt these circuits!
The top one uses quad NAND gates (HCF/CD4011). The lower one uses a jk flip-flop (HCF/CD4027).
I thought using 4000 series chips might be easier with a 12V supply. However, vehicles are harsh places for electronics and you need to take measures to protect the circuit from damaging spikes, noise, higher-than expected input voltage etc. I'm no expert in vehicle electronics, perhaps other forum members can suggest what might be needed.
