Two years ago I finally had a chance to drive two laps on the Nurburgring, or as Jackie Stewart calls it, “The Green Hell”. I did it on a dampish drizzly day and it was, as Jackie said it would be ... a great and humbling experience. I only saw two cars off in the willy-wags in my two laps, there is an ample amount of dumb out there. The problem is that the course is long, has more turns and grade changes than you can quickly learn. The problem with simulators is that they don’t give you about the chacterisics of the car you are driving. Is the breakaway abrupt or is there warning? Does it go out oversteering or understeering? What happens when you hit the brakes while cornering? These are all important questions you never want to find the answer to, and that takes judgement. A simulator may help you learn where the turns are but it will not tell you when a stalled car is just around the blind turn or if someone has had a minor off road and tracked a load of pea gravel onto the pavement right at the apex of the turn. I spent the first 20+ years of my automotive career as a ride and handling development engineer. I started out young and stupid about vehicle handling but the guys I worked with, bless their souls, quickly fixed stupid. I learned performance diving on a closed handling course, not a stupid skid pad with paint stripes on it. So what is your brother’s background and driving experience .. some 19 year-olds have had the opportunity to gain the requisite experience, most have not and you need to figure out where he falls.
If your brother wants to experience good fast lap around the ring, the best way to do it is in a ‘taxi’. They have some well prepared BMW Sudan’s driven by guys who have done hundreds of laps and can safely give you a really quick ride and while not cheap, for less than the cost of renting one of their cars.
Actually you either own the car you are driving or you have to rent one of theirs regardless of age because of liability. Insurance is a policy specific issue best handled beteeen you and your insurance agent. I would go with the lower performance level car since the limit handling will probably be more predictable although we both hope your brother will never find out. It helps that there are no timed laps on general public days since each lap begins and ends going through a toll gate on an exit or entrance lane, at the price of a lap, they don’t let you out there on the honor system counting your laps. Hope it goes well, it is a neat place.