(a) The driver of a motor vehicle shall not follow another more closely than is reasonable and prudent, having due regard for the speed of such vehicles and the traffic upon and the condition of the highway. Except when overtaking and passing another vehicle, the driver of a vehicle shall leave a distance of at least 20 feet for each 10 miles per hour of speed between the vehicle that he is driving and the vehicle that he is following.
(b) The driver of any truck or motor vehicle drawing another vehicle of 25 or more feet in length when traveling upon a roadway outside of a business or residence district and which is following another truck or motor vehicle drawing another vehicle of 25 or more feet in length shall, whenever conditions permit, leave sufficient space, at least 300 feet, so that an overtaking vehicle may enter and occupy such space without danger, except that this shall not prevent a truck or motor vehicle drawing another vehicle of 25 or more feet in length from overtaking and passing any vehicle or combination of vehicles.
(c) Motor vehicles being driven upon any roadway whether a business or residence district in a caravan or motorcade whether or not towing other vehicles shall be so operated as to allow sufficient space between each such vehicle or combination of vehicles so as to enable any other vehicle to enter and occupy such space without danger. This provision shall not apply to funeral processions or to any parade or procession authorized by official permit of the governing body of the city or county having jurisdiction over said highway.