What is the continous speed of lowest consumption?

I agree. I have a fixed route to and from work, 17.4 miles, part rural, part highway, and my mileage has consistently been <50mpg when driving 60mph and almost 60mpg when cruising at 55mph. Both times with cruise control on.

My tank this time is averaging 43mpg. I expect to see better than 50mpg on the next if I drive 55 and under only.

 

That is true with most vehicals, When towing a trailer over 1000 miles twice with an explorer w/5.0L, I got about 15 mpg @75mph and about 22 mpg @ 60mph through mountains

 

Update-- 52.1mpg when driving 56mph and under. I had 55mpg for a little while, but in-town ferrying of children killed it.

I am going to inflate the tires to 42/40 and see what improvement I get.

 

Yeah, that kid ferrying will do you (and your mileage) in pretty fast.

BTW, my 60 MPG 40ish miles at 55 MPH was on Nokian RSi snow tires, pressures 42 front 40 rear. I would theoretically have done better on summer tires.

Some time I'll have to go somewhere basically flat to see what difference that makes. Can't go anywhere here without hitting hills. I don't know if nearly pancake flat Kansas roads would provide noticeably different mileage.

 

I live in Cincinnati, Ohio and here, it is very hilly. I ran my 2008 on the highway for the first two days and decided to start taking the very direct but hilly route 50 into the city. P&G for a week, netted me 41.8. CC for a week was 43.1. There was a cold snap in both weeks and my car is NOT broken in at this time. But just from my very un-scientific test, (I wish I understood how to make graphs like some of you here!) I think using CC and strictly following the speed limit is the way to go. BTW, speeds in my case on Rt. 50 vary from 25MPH to 50MPH, with an average, (again, attained un-scientifically) of 43MPH.