Car LEDS that change brightness according to RPMs

I was just laying here, pondering what to do to my car to make it unique, and was wondering if anyone has been able to use a tach wire as an input. I suppose the next question would be whether or not it can be used at all to read the RPMs of the engine.

My project that I’m thinking of involves using some leds behind the grill of my hood scoop and side vents that will vary in brightness according to the RPMs of the engine. Voltage peak would be max 14v (again, assumption). So at idle I would set the brightness, then have it increase as the engine rpms increase.

My problem isn’t wiring or programming the Arduino, what I’m wondering is how to connect it to the vehicle to read the RPMs.

I found this on parallax.com. There is some discussion near the end of this thread that may help.

EvilSpl0it87:
if anyone has been able to use a tach wire as an input.

Many people have done this, if previous threads on this forum are anything to go by.

what I'm wondering is how to connect it to the vehicle to read the RPMs.

That depends on the actual signal your specific vehicle produces on its tachometer.