A Tiger is now faster on a road than infantry (7 hexes v 4 hexes) and as fast as infantry in clear terrain (3 to 3). In this context we are talking about combat movement so an effective 3km/hr on an exposed road doesn't seem crazy, especially if the platoon is to retain cohesion. I'm not defending the choices in 3rd edition but in playing with them I have found that the changes that I thought would be very detrimental to the game have not been as dire and several of the changes have played positively.