G'day from Sydney Australia,
I quite like your bluetooth-> car control idea, and would be quite interested in helping you develop your idea to a working prototype. I'm an Electronics R&D Engineer with 25+ years experaince developing PCB's and turning idea's into products.
My bid is just for 60hrs work, normally, my rate is $75/hr but I have quoted $50 for you and this project for add hoc PCB design and programming, as this project may take a little time fro all parts are fully sorted, from BoM, to Schematic, to PCB artwork, to enclosure etc, as well as documention, and then firmware etc. I and my team can do this all for you, but let just chat and get started at the begging and see where it all leads for you.
I look forward to working for you on ths BT <->Car idea.
Cheers,
Darren