^ I dont agree with that for the full 100%.
First of all its not cold that induces wear, its lubrication (or lack of) and differences in tolerances.
Secondly, forces when driving (even when driving gently) are in an order of magnitude bigger than when idling.
Oil can take some time to refill all the passages, sometimes up to a half a minute or so (you can see that when you have had an engine apart and start it up again it takes some time to get oil pressure) . In that situation you want as little force on the wear surfaces as possible.
Also when things heat up more quickly, it means that some parts heat up more quickly than other parts as it takes time for heat to travel through the metal. That can mean that some things expand more quickly (due to heat) than other things that they wear upon to, changing clearances.
The general advice to drive straight away is that it causes less pollution. A heated up engine is less polluting, and driving straight away means you use the energy otherwise used as idling directly for driving.
There was once a video by engineering explained where the argument of when a car starts cold, it makes the mixture extra rich which can cause droplets of fuel on the cylinder wall infilcting wear and that more quickly heating up the engine will make the mixture lean more quickly.
In a way that is true, but all modern car has a so called open loop and closed loop state. In closed loop the mixture is adjusted to its need, and in that situation the statement of engineering explained is true. However, every car waits for around 50sec-1min for the lambdasensors to warm up to go to that closed loop state (without the lambda sensors working properly, it doesnt work). This is a set time (there is no temperature measuring involved). Until that time, the car runs in open loop. That means it has a non adjusted pre-set mapping that is thus not adjusted by the need of the mixture. The amount of mixture is injected by measurement of the inlet temp sensor/MAF and the throttle position and not adjusted by the lambda sensor (that can measure if all fuel is burned or not), so for that first 50 sec-1min the mixture is rich anyway, regardless of driving or idling. And if that preset mapping is set correctly, you get to the point that there is way less fuel in the cylinder cavety when idling than when driving, which means there is less fuel to condense on the cylinder walls and because less air (and less gas) is let into the cylinder all together (because of the closed throttle body), the vapour point is even more shifted, resulting in even less chance of fuel condensing on the cylinder wall.
That that guy didnt even mention closed or open loop says to me that he overlooked that. Only in closed loop the engine can lean itself out, but that only starts to happen 1 min after its started.
Thats my view on it anyway.
So when really cold, let it idle for about a minute imho.
Also a z4m will take a lot longer to get hot/to get to operating temperature because of the iron block (iron is a bad heat conductor and has more heat capacity, so it needs more energy to heat up and it gets that energy more slowly). This means heat is distributed more slowly through the engine.
Seriously tho' I'd get it looked at. That's not normal.