A trucker handed in a ticket at a toll booth showing that in 2 hours the truck had covered 159 miles on a toll road with a speed limit of 65 mph.

a) Calculate the average speed of the truck during this period.
b) Determine if the truck exceeded the speed limit at any point.
c) Discuss the implications of the truck's speed on toll road safety.
d) Analyze the fuel efficiency of the truck during this journey.