I have several cars that are kind of ambiguous, but they do have a 210 mark in the dead centre, and a 100 mark at the left, and a 260 mark at the right. (One has tick marks that don't appear to sit at rational numbers.) If I use a 212 degree thermostat, the needle sits right at 210. With my temp gun at the head where the sensor is, I forget the number, but it is something very consistent, but higher than that. If I use a 180 degree thermostat (which I normally do), the needle sits right where you'd expect a 180 tick to be, and yes, I've measured.
I don't know if it's intentional, but the reading is close to the marking on the thermostat, not the actual temperature. I imagine it is intentional, that if the gauge reads consistently higher than the thermostat, some people would complain, much like the impedance figures of audio amplifier inputs.
In any case, I have four vehicles from 1990 to 2000 that have the same gauge, yet different electronics, and all read the same.
I have two other vehicles which have different gauges, but the same as each other. One is a 1981, the other a 1988. There are no markings on the gauges, but, with different thermostats they both show the same reading for each respective thermostat. My 180 degree always puts the pointer right at the low mark above the "C". I have had both of them up above the "H" for various reason, and I have no idea what that actually means. But, being the motors they are, any damage sure isn't apparent after many, many years.
