Surprisingly, you can actually go fast round a corner in OMSI, except it needs to be quiet a wide, obtuse corner rather than like a sharp bend, and then you should only tap slightly the direction your going in, enough for the bus to follow the corner naturally rather you drive it around. also maintain a steady speed or slow down slightly, but dont accelerate too much. then you can take a corner fast like in a real life. if im honest, when drivers take a sharp corner in real life, it is a very uncomfortable for both the driver and passengers, and you dont see it much (only at junctions)