In perfect convective heat transfer, the heat transfer coefficient will be constant and "Newton's law of cooling" applies, so then yes, with changing ambient temperature a new equilibrium will be reached where the temperature difference is the same as before; i.e. 1 degree hotter room = 1 degree hotter cpu.
BUT... to quote Wikipedia: "The heat transfer coefficient is often relatively independent of temperature in purely conduction-type cooling, but becomes a function of the temperature in classical natural convective heat transfer. In this case, Newton's law only approximates the result when the temperature changes are relatively small."
In open cases, Newton's law will almost certainly be a good approximation. Maybe the lack of circulation in druck's fridge explains the slight divergence there, and I don't know WHAT happened in the car.