Vehicle rollover protection system with a roll bar, whose top piece is rounded in U-shape

A rollover protection system for motor vehicles comprising:

• a roll bar, having a top piece that is tubular and U-shaped, wherein at least the tubular top piece consists of at least two axially divided partial tubular shells of sheet metal, joined to each other and having different geometrical shapes corresponding to a nominal contour, wherein the roll bar is configured as a U-shaped roll bar with the top piece and two parallel legs for each shell, wherein not only the top piece, but also the legs consist of partly tubular shells of sheet metal, joined to each other, and wherein the top piece and the two parallel legs of each shell are formed as a single piece, wherein the shells of the top piece are padded with a plastic jacket, wherein the shell adapted to face one or more passengers of the vehicle is configured partially or predominantly flat, and the plastic jacket in this region is thicker than on the other shell.