@srinathdevelopment
Thank you so much! I will start playing with that and see what questions arise.
@liudr
Depending on your automotive electrical skills, you could use a simple relay setup like this > Special Applications with SPDT Relays
I've used this before so that the cars stereo stays on after the key has been removed, but turns off when you open the door (also provides power during cranking since it would be separate from the accessories). Only difference is that it would connect to the arduino instead. You can buy cheap DIY female car cigarette lighter plugs.
Otherwise, the capacitor sounds like a good idea (might be expensive though?).
Sorry again for the bad forum etiquette! 