NeedWhy do we keep using keys to enter cars? Isn´t there a better way? Wait! How long have ZipCar existed? Why haven´t we adopted ZipCar way of opening cars? Imagine having 2,3,4 cards to open the same car. In a family of 3+ this is a constant battle. In countries that have a lot of traffic and laws to limit the cars on the road (e.g. Mexico, Colombia, Chile, etc.), people have the additional problem that need to switch cars every other day, this is a very tedious task when you only have one key for each car.
Get the ZipCar system of opening car doors. Create an "Initiating Kit" that local repair/garage shop can install pretty easily with some instructions. Probably consider signing up some local repair/garage shop at the beginning to guarantee the quality of the installation.
Charge for the "Initiating Kit", for extra cards and configuration. I am thinking we can probably charge US$20 per "Initiating Kit" without the installation and US$5 per new keycard. Only in Bogota, Colombia, we have a million cars on the road. Assuming you can expand to 100 cities like Bogota in the world this is a US$2.5B market. At some point, we can make this system pretty competitive and good so we can sell it to car manufacturers directly.