On cold start, especially in colder weather, is not a bad thing to allow proper oil circulation before setting off, which can take a few seconds, i usually let it idle for 15/20 sec in warmer weather - it is not a big deal, the time to fit the belt, set up the infotainment, and such. On very cold say a minute or two.... Important thing is to be gentle and progressive in stepping on the skinny pedal, unless you are in a hurry, no sense to gun a cold forced induction engine. And as travs mentioned, respect cool-down times. What Berisford's neighbour does is bad from mechanical perspective, and not only. Now your 280 has also GPF, which means sometimes the engine management system will increase RPMs in order to heat, pre-heat, or run whatever cycle it runs with the GPF. While can be alarming at first, it is normal .... If I have to manouver and it goes on fast idle, I wait until RPMs drop before turning off, something worries me about cutting off who knows what process that might set off a fault ....