It is a 1998 bmw 325I... The car was running fine. While driving down the road the head lights were very dim, all the dash lights were dimming so we pulled over and the car died. We sat that for a few minutes and tried to restart the car, but it didnt even have enough power to turn any of the lights on.... What could cause this to happen?  Could the battery being dead cause this??? Im going to be going to get a new battery in the next few days... but I really have a hard time believing that the battery being dead could cause the car to die...

thanks