Why do people change their speed all the time? Last week I was overtaking a row of cars in the middle lane and had a Prius on the outside lane going slower than me indicating to pull in when he was level with me - I put my foot down to let him merge behind me. 5 miles later he bombs past me at about 90 when I've kept the same speed 
	
		
			
		
		
	
				
			
	
 
) then I move to the outside lane well in advance to get past and if need be adjust my speed. 

