Where do I start?
I have just brought a E39 M5 my dream car

after 140 miles ( almost continuous driving)the water temp gauge jumped from normal to over the red like it had been flicked. I stopped the car and turned off the engine, when I turned the key back on the temp showed normal

The oil temp gauge wasn't affected. I checked the engine which didn't seem hotter than any other engine and the heater matrix was still providing hot air into the cabin.
I continued to drive home (approx 5 miles) just as I pulled onto the drive the temp went from normal to over the red. I turned the engine off and the ignition back on...temp normal.
I am in the process of trying to get the dealer to sort or take the car back however if I do end up holding the baby, I would like to know what it my be and what is cost likely to be

This car is great in every other way but don't want a potentially damaged engine.
You guys have been very helpful in the past with my E36 325i and I am hoping you can assist again.
Many thanks
Marc