GPS Digital Speedometer for Car MPH, Universal HUD Speed Meter with LED Large Font, Plug Play for Car Truck Motor SUV Golf Cart All Vehicles (HUD Speedometer (Green Display))

Well it's better than having no idea what speed you're going.... But it's definitely not very accurate and it is very bright so make sure you place it properly so it won't Blind you driving at night. The design is cool though

Wish I never bought it don’t understand how it calibrated. It makes all kind of weird noises and does what it wants. I actually threw it in the trash.

I like the idea of this heads up speedometer, but it's execution leaves a lot to be desired. Because it's based on GPS, I found it to be very inaccurate - it reads about 10 mph fast. (so If I'm driving at 20 mph, according to my car's speedometer, it shows me as traveling at 30 mph) The big flaw is that it's useless if you wear polarized sunglasses. The polarization filters out the reflection and makes the readout impossible to see.