Me and my friend love geeking around with our first cars, specifically adding gadgets to them. A few examples of what we've done:

He's built an in car ambient lighting system and made his electric windows and car radio voice controlled, I have built led strobes into the front grill that dazzle speed/parking ticket cameras & fitted gas struts to my bonnet; aka the same as the rods that make the boot rise automatically when you open it.

I have 4 blank buttons on my dashboard and would love to add some extra functions to these, but I want these functions to be really unusual or neat, not just like heated seats or something. I'm thinking along the lines of something James Bond like a smokescreen or I had an idea for an external audio amplifier for eavesdropping which plays through the speakers, but I cant think of 4 or more realistic things, ie no missiles or invisibility lol. Everything would be for show or off road use of course. I'm willing and fairly competent to try building anything, though. Does anyone have any cool ideas?