My suggestion is to use proximity sensors to provide "Blind Spot Sensors", back up, and front sensors to an automobile. This is a $1000+ feature on new cars, but could be done for about $100---BUT it could be done way cooler with voice alerts via MP3 file triggering with a heads up display.
I know exactly how to pull this off as I built an R2D2 that has proximity sensors and "smart" MP3 triggering. I'd love to partner with you and can provide to the donor car, the parts, programming, 3D printing, script, Video Editing, etc. My 11 year old son and I have an ad-free youtube channel with a whopping 58 subscribers to inspire kids to learn and become awesome adults.
We'd be honored to be on the same "virtual" screen. (We have green screen mojo). We could send you our solution's design plans and code, film the install on our end, and show the test drive.... or if you'd rather, separate out the effort.
Let me know what you think.
Thanks,
Sean J. Miller