Taken from carguide:
https://www.************/2018/04/rev...sport.html?m=1

"Apparently, the CX-9’s engine components are susceptible to heat soak, especially when driven at high speeds for an extended period of time (in this case, a steady 100-110 km/h for about 4 hours). Whether its due to the high ambient temperature or not, what matters is that the engine temperature rose steadily, resting at about three-quarters to red (110 degrees Celsius according to the gauge cluster)."

Could it be that its a just a matter of a shitty engine design? Guess I wouldn't be buying a Mazda with turbo now.

Edit: Crap the link won't work. Oh well. It's from carguide's CX9 review dated 2018.