How do I better mpg with mostly Hwy miles ?

Definitely the other road and pulse and glide all the way to the hwy if traffic will allow this ..
1. What PSI are you running should be at least 44(front) and 42 (rear)
2. The use of a Engine block heater would help also..
3. If you are only going 29 miles on hwy try 55mph and on any big downhills turn cruise off and glide .
4. when getting on the hwy accelerate slowly and when getting off turn cruise off before exit and glide if traffic will allow.. You want to try and be almost not moving when you get to your turn or stop when exiting hwy..
5. Drive like you have no brakes count the number of times you hit them..I am not saying run lights or stop signs but try and time the lights where they are green and you don't have to stop . Stop signs let off early and coast up to them..
6. keep us posted of your progress...

 

This past week I made two trips on the highway of extended milage for the first time in a while. This was the first time that I had made a longer trip with higher tire pressures (50 or so all around) and set the cruise at 59-60. A trip from Morgantown WV to Pittsburgh PA was 66mpg on the way up, average was down to 64 by the time I got back (175 miles round trip). Morgantown to Washington DC at the end of the week gave 60-61mpg for the roughly 650 miles of driving. I had never seen milage like this on the highway until the tire pressures were up and I pulled back my speed. I'm sure that some of the increase is the better broken in car (15000 miles now) compared to much lower the last time I did such a long highway trip. The temperatures were upper 40's lower 50's so I had upper completely blocked and lower blocked saved one slat. (Temperatures were perfectly normal even during the climbs of Marlyland and WV) I would definitely recommend the grill blocking (to some degree only if you don't have a way to monitor temps). Hope the my long drawn out two cents helps

 

i find i get better fuel economy on the freeways by staying in the right lane with the cruise set at 55-62. the 30 minute history looks more or less even.

with the cruise control off, the 30 minute average is all over the place, and not even

i seem to have better luck with going up to speed, letting go of the pedal first, and
then setting cruise vs setting cruise and letting go of the pedal afterwards

on downhill runs i turn off cruise, and keep foot off the gas pedal

 

Try this on downhill runs: Turn cruise off and slightly push on gas pedal and your speed will increase. This is called super stealth and it works a lot better than just keeping foot off gas pedal..Here is a pic of what you should see:

 

kingskid,

definitely check all your tire pressures often. Keep a good gauge in the car. I'm running 38 psi front/ 36 psi rear. My highway mileage has been well over 50 mpg.

I didn't like using cruise control on hilly terrain at all. I turned that off immediately.

Let us know of any non-stock or anomalies on the car.

Are you running 87 pump octane, name brand fuel?

 

if its like a 6 % downgrade, sometimes i actually accelerate up to 70-80 or so without even touching the gas pedal and the picture you provided matches what i am getting without
touching the gas pedal. ill have to try the gas pedal on downhill runs that are not as high

 

Increase your tire pressure to 42F/40R.

Use your cruise control on the interstate and keep your speed at 60 MPH or less. 60 MPH = 60 MPG in the Prius.

Learn to pulse and glide in town. Try to keep your speed below 41 MPH.
Learn how to consciously manipulate the gas pedal to attain glides and warp stealth. Lift your foot completely off the gas pedal and lightly reapply to cancel all arrows below 41 MPH, or attain yellow arrows from the battery above 41 MPH.

Be patient and committed and the results will astound you. Routine 60 MPG tanks will become effortless.
Be aware, Winter and colder temps are going to hinder your efforts.
Until the northern hemishere is leaning toward the sun again, next year, and things warm up again ;.)

 

Being that the OP is in North Dakota, grill blocking will probably be necessary to get decent mileage this time of year. Even here in Missouri I'm seeing serious mileage hits when the temps drop below 40. I haven't done any grill blocking yet, but plan to block the top later this week.

I can tell some difference with the mileage when the pressure is below the 42/40 I've been setting it at.

Also, I keep my oil level about 1/4" below the full mark (by adding 3.5 qts. to a fill, rather than Toyota's 3.9 which will put you about 1/4" higher than full.) I also run Mobil1.

I'm still trying to figure out the cabin heating/cooling. It was absolutely killing my mileage the other day in 39 degree range, but I had to run it some to keep the windows from fogging. (I was comfortable with the interior temp as the vehicle had been garaged.) Having to run defog/defrost seems to keep the ICE on nearly all the time. On the return trip two hours later the temp was about 12 degrees warmer and I could see about 5 mpg difference on the average of both 45 minute highway trips.