Last weekend I visited the Porsche museum in Stuttgart, a great exhibition of the sportscar:
forget about flat 4 or flat 6 engines, flat16! = 16 cylinder twin spark "boxer" engine =32 spark plugs + mechanical Injection
For me, one of the most impressive cars, the Porsche 909 Bergspyder, less than 400 kg weight!
For any gearhead: If you haven't been there - you have to go there!