Best MPG - AC or bust!

Yes. Slow down. Using the Prius MPG Simulator, steady-state 70 MPH with no winds on level terrain in 50F temps should net you ... 44 MPG. Slowing to 55 MPH should net 54 MPG under the same conditions.

A variety of factors will drop it even more in either case, including a head or cross wind, lower temperature, underinflated tires, hills, and frequent accelerations and decelerations.

 

I understand. There are highways here where 55 could get you run over. Are there any byways that might be practical to use? I avoid the interstate unless it's time-prohibitive.

The point of course is that your fuel economy is within the range of "expected" for your driving conditions. There may be other small things that will help; Tideland's advice is good. Based on your route, I suspect your terrain isn't hilly. But if you have any steep uphills, you might consider killing cruise control on them. CC is very aggressive in maintaining speed, and pushes ICE RPM into high inefficient ranges when climbing. Instead, use downhill momentum to get a run on the next hill and let speed bleed off somewhat as you approach the crest -- staying safe and legal at both ends, of course.

Expect it to get worse as winter sets in. Cold weather hurts fuel economy in any vehicle.

 

I typically run my tires in the summer at about 40 psi in the winter i go down to about 33. I have also experimented with windows up and down, air or none, and windows up with the air on is much more efficient than down. Plus the wind buffeting with the front windows down will rip your ear drums out. lol In the summer i average about 45-48 mpg and winter it goes down to about 38.

 

Try slowing down a little. 55 mph will get you run over, eh? I wonder what the trucker speed limit is......

Try 60 mph, or 62 mph. People will still be flying by, but you will be keeping up fairly well and much less likely to get "run over". In California, Hwy 5 would be analagous to that. Speed limit 70 mph in most areas, to drive 55 would be bad (unless you found a law abiding trucker, then just tuck in a safe distance behind him). I drive on hwy 680 and on the weekends, it is hard to drive 55 mph, but I do it anyway, in the far right lane. During the week it isn't as bad, because traffic is heavy enough that everyone is slowing down a bit.

I miss driving in Hawaii. Unmarked cars with radar. Everyone drove the posted 55 mph speed limit. It is so easy to drive that speed when EVERYONE else is doing it.

Too bad we are a spoiled, self centered, instant gratification oriented society/species that we can't move beyond our own petty desires.

Grrrr.

 

I've found (on the piedmont hills of upper Georgia Interstate) that If I aim for between 63 mph and 66 mph, I can get 54 mpg consistently on average. This means that I will very slowly let myself go up to 66 downhill, but uphill I very gradually press the accelerator down more to try and match proper throttle to maintaining minimum 63-64 uphill (as to do a slow engine power bleed in). The MFD shows uphill that I'm averaging no less than 30mpg. As soon as you top hills, let up and very gradually get up to your max speed again. For flat driving, aim for 65 and you'll do well.
I run tires 38/36 also, and had no noticeable break-in period for mileage differences.

Cruise controls aim to always hit their desired velocity, and can sometimes hurt fuel economy by sometimes requiring excess throttle to reach their specified setpoint, rather than having an acceptable hysteresis range as I mention above.

 

I'm routinely in the 65-80 range over a couple of medium mountain passes, and have a lifetime average of 51.2. I do 90 miles a day, and have 48,000 on the car in less than 2 years. Run the tire pressures about 42/40, and I use the AC at a comfortable level. I don't see how anybody can get less than 50. I don't try very hard at all.

 

Slow down and use the right most lane to allow fast drivers to pass you on the left. Safety first. Tire pressure no lower than 38F/36R. Using cruise control is not a bad idea. Make sure tire alignment is good.

 

Again, with your conditions, your results are not out of the ordinary. With all respect to Subarutoo, you can get less than 50. His climate is warmer than yours, and temperature makes a big difference.

Since you seem very interested in maximizing fuel economy, I suggest you study the various fuel economy threads and put into practice the many techniques that others offer. There are opportunities for improvement, as we've suggested, but anything beyond the basics will take practice and patience.

 

mpg

Several things when taken altogether will help your mileage.

1. Inflate tires to 42 up front and 40 in the rear

2. At your first oil change go with full synthetic oil like Mobil 1

3. Only add 3.5 quarts its plenty and if you put in 4 it WILL reduce your mileage

4. Don't use your cruise control as much so you can get used to the light foot on the accelerator. You will see the MPG bar go up to 100 MPG much more than when using Cruise.

5. Cold weather will reduce your MPG

Also remember that true highway driving will reduce your mileage from city driving. My wife drives to Boston and back every day (about 65 Miles total) in lots of stop and go traffic and she gets about 54 MPG from April through Nov. and from late Nov to early April she gets 46 - 48. The engine (ICE) runs a lot more in cold weather. I drove to Hartford and back (all highway) at under 60 Miles per hour and got 59 MPG.

It Will improve as time goes by and as you get used to driving and follow the recommendations above.......