I have a V8 5.0L engine (bottom left pic) and 50 deg C is definitely not normal. SB more like 80-90 deg C running at highway speed on a 'normal' temperature day.
Looks like the temp gauge in panel is maybe sticking or broke. If car seems to run ok, the ECT sensor is probably ok.
If you can read DTCs (diag codes) from car, do so. They may help you figure out what is wrong.
But there are a lot of 500E/E500 owners here to advise you.
Regards . . . . JimF
'94 S500 Cpe
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