Just fitted my side windows and I found that a normal drill bit is fine, try and find a fairly blunt bit as it will cut slower and also take your time. A year ago I cracked one of my headlight covers - using a brand new bit.
Also once you start drilling keep the drill held solid as any movement other than towards the work will crack the plastic. A piece of wood behind the plastic helps and I also just used the weight of my drill as the pressure on the plastic.
Also once you start drilling keep the drill held solid as any movement other than towards the work will crack the plastic. A piece of wood behind the plastic helps and I also just used the weight of my drill as the pressure on the plastic.