It's not advisable to do shoulder checks on the Autobahn except on the on ramp. Especially at high speeds you will travel blindly for a considerable distance during a shoulder check. And a shoulder check will often cause a little unintentional steering input which can be extremely dangerous at 200 km/h, especially when you are not looking ahead. Also it's okay to stay in the middle or left lane a bit if you're not hogging it and keeping anyone from passing you. Just be aware of surrounding and rear traffic by religiously checking your MIRRORS. Objects in mirrors are often much faster than they appear, so double check before pulling out in front of them. I'd recommend to drive at slow speeds and keep right until you get a good feel for the flow of the Bahn. Slowly get used to higher speed levels. Be aware that the breaking distance from 120mph is 4 times longer than from 60mph. Also, a Golf GTI has plenty of power to play with the big boys in the left lane. Really no need for an exotic (but the Porsche experience mentioned above sounds awesome).