It's a cool gadget! Why would I need the nightvision scope I bought!
Seriously, the real reason is if you are into motorsports or tuning which I assume a number of RX8 owners will be into.
You can check your tire temps. A reading on the inside, middle, and outside of your tire tread will tell you a lot about your's suspension setup and that is handy for changing setup or tire pressures.
You can also use it for spot checking intake or exhaust temps.