The presence of temp gauge in vehicle, whether it must have, should have , better to have or no need to have is ongoing debate among vehicle users and can not concluded by just to consider ECU intelligence, your favorite area of interest:P.
Temp gauge is nothing to do with ECU temp control. Its just indication that ecu is doing its work.
The fact that vehicle manufactures have omitted temp gauge in their particular model is some thing else. From what I understand, manufacturers do not want to feed the drivers with many info. Also, newer drivers do not care much about this info.
They have even secondary claim for this as their ECU has enough intelligence so they dont need such gauge. Rather they have considered it as because of consumer psychology since owners are more likely to drive gently?and ?not thrash the engine??if there's a light on than if the temp gauge simply shows cold. Similar case is with high side. Don't drive and just cool down if that light is ON.
New engines that have not temp gauge, there are two light for cold and hot.
While reached to hot light engine have reached some distance up to that light, If no temp gauge then no indication it is going in that direction.
High temp light on dash may corresponding to H position on gauge. Its better to drive engine just below H position?. Below H, no light.
The justification for omitting the temp gauge can only rely on intelligence if that intelligence could shut down the engine, if engine is over heating or damage going to occur soon due to over heating.
If ECU does not shut down engine when over heated, rather it is done by driver after damage has been occurred by his observation then intelligence go to......
No ECU manufactures can be called for recall it damage has been occurred due to coolant system fault like depleted coolant , rad fan fail or other because since their ECU was intelligent but it could not prevent damage.
Some one who has faced damage due to absence of temp gauge would be wiling to have because it could give him indication of engine over heating or before the head gasket was cooked . My colleague was one of them. His city 06 ECU intelligence could not prevent (it did not shut down engine) engine from damage while coolant was all depleted and he had to swapped.
If u ask from manufactures if they have omitted the temp gauge for reducing cost, their answer will definitely be NO. But it has some truth.
In the future, if there is no speed limit on roads around the world, the manufactures might think to omit speedo gauge. They will just provide one light. It will turn ON when vehicle owner is driving at such speed that is dangerous for vehicle, I THINK.
And their claim for omitting this will be, less gauges, less focus diverted from road to see investment cluster. No gauge mean, eyes Alyas on road.
Some one who has worked on cost estimation on products also has the job to find ways to reduce.
If he has find ways and reduced by just 50 $ on one piece and company has produced 50,000 unit, then.......................
At the end, WHY TO THINK THAT THE ENGINEERS AT VEHICLE MANUFACTURES (TOYOTA OR OTHERS), SORRY I DON'T KNOW IF UR VITZ HAS TEMP GAUGE, ALWAYS ALWAYS THINK BETTER THAN USER FROM OUTSIDE.