I have had it for several years in an Opel Corsa D CDI connected to the brain's socket, water temperature, speedometer, tachometer, consumption, turbo, indicator shutdown, etc. ... It was connected by an auto electrician and works perfectly fine ...

Installed in an Opel Corsa D 2007 1200cc. I put it in for checking the water temperature. According to the car's hidden menu, the various temperatures were just 1 degree apart. Detailed indications-malfunctions:
Positives: Water temperature, tachometer, speed, battery volt, clearing faults (Check).
Negatives: Does not show oil temperature, consumption, and all the rest. The glue on the base is not sufficient; use another double-sided tape.
Every now and then, at least once a month, I had to unplug the cable from the back because it would get stuck and wouldn't turn on.

For the money it costs and what it offers in terms of features, it is very good; I still don't know if it is 100% accurate, but it's better than not knowing anything at all

I've had it for about 5 years, I can't say that the indications for water temperature, oil, etc. are accurate but they're close enough, it doesn't even read the brain (Volvo XC60 2012), not to mention that a couple of times it short-circuited the gauge momentarily and the lights turned on by themselves. You get what you pay for, of course.

Unfortunately, it does not work on a 2015 Toyota Aygo mk2. It does not connect (protocol failure). It works on an Opel Meriva 2004.

It does what it promises. It solved my temperature issue because my car doesn't have a temperature gauge.

Variety of indicators with a small delay but cheap construction materials for its price. The screen is very small and the lighting during the day is insufficient to non-existent.