I have an '08 FEH that is currently getting 33.2 MPG. (If they ever update the site I'll get it into the database so I can have a cool banner!) Anyway, in a couple of weeks I'll be going on a long distance trip (175 miles each way) that is at least 90% highway. Since fuel economy is better in city driving than on the highway, will I take a huge hit? I've taken this trip several times and usually put on the cruise control as the police are particularly willing to meet you along the route.
I know this sounds silly, but I hate the idea of working so hard to get the readout to say "33.2" and then watching it drop.

 

Hi Mary,
When I bought my 2003 Prius, I flew out to Fort Worth TX to pick it up and drove over 800 miles back to Huntsville AL along a fairly flat, I-20. I broke the trip into ~100-150 mile segments and used the cruise control at speeds from 60-75 for each segment. This let me calculated the MPG vs MPH mileage:


You might consider doing something similar on this trip. Just break it up into say 2 hour segments using cruise control to hold the speed. Be sure to identify if air conditioning was used and characterize the route (aka., hilly, flat, climbing, descending.) This will give you some number to use on the return trip. I'd especially recommend one early segment at the highest cruise speed you want to use followed by one segment at the slowest you feel comfortable with.

GOOD LUCK! and a safe trip.

Bob Wilson

 

Mary... The FEH's MPG is excellent at 55 MPH. If you can choose a route where you could maintain 55 MPH, I suspect you will stay close to 33 MPG, or maybe even higher than this. Using your foot on the pedal to keep RPM steady vs. speed steady on small hills will also keep MPG at its best.
In other words, it has been shown, cruise control in the Ford hybrids reduce fuel economy by 1 or 2 MPG. Also, do you have 44psi in all four tires? More air in the tires will raise MPG by 1 or 2 MPG also. 44psi is safe for all speeds, but you will feel more "bumps" in the road than at 35psi. You can choose if 1 or 2 MPG more is worth feeling the road more.
-John

 

Luckily, the route is mostly flat. I would probably be okay with higher PSI, but how rough does the ride get? I am driving injured right now with a bad back and hip, so feeling lots of bumps might make me miserable, and though good mileage is wonderful, so is my sanity. At least, what I have left of it.

 

I say try the tires at 44psi for a day and see what you think.
It's very easy to let some air out ( and as long as you have a pressure gauge with you, you can get it right to 35psi, anytime, anywhere). Getting them filled up is the hard part.

I agree 1 or 2 MPG gain is not worth additional pain.
But, you may not notice any difference.
I depends a lot on the quality of your local roads too, of course.
-John

 

Mary,

My mpg always takes a hit on road trips. I've tried a lot of things I've read about here, but nothing seems to help- I tend to drive too fast, use too much air conditioning, etc. I work hard on my fuel economy in my daily commutes so when it's time for a trip my new attitude is to just put the cruise control on and enjoy the view!

And if you do well on your trip don't come back and mention d-r-a-f-t-i-n-g as one of your techniques or you'll get a bunch of members riled up about safety.

 

Excellent advice and I find cruising between 60-65 mph to be a lot less stressful. I love to zen out on cruise control, quality tunes and a calm attitude rolling down the highway.

Here are some useful "d-r-a-f-t-i-n-g" guidelines and professional truck driver advice. Another approach is to use large, slow moving vehicles as cover for fuel efficient speeds.

Bob Wilson

 

Thanks everyone. I talked to my dad about the PSI trick, and he said it does work well but shortens tire life considerably, and a new set of tires is rather expensive. I think I'll just live with good ol' 35 PSI.
I won't use the D word, but I never follow big trucks closer than one second, and the ones on my route are all logging trucks, so I'll stay away from them entirely. Decapitation doesn't seem a good trade off for higher MPG.
I hit 33.8 MPG average today on the way in to work. I can't wait till I get a Scan Gauge (my birthday is coming up!) so I can see how well I'm doing on my individual trips. There's a spot in my commute where I can put it in to neutral and drive for about 2 miles. Who thought river valleys had a purpose?

 

Mary, print this out or show your dad.

#1 These hybrids have special LRR hybrid tires that your Dad probably didn't know about. They have a special "harder" rubber compound and perform better with higher psi.

#2 More air pressure EXTENDS the tire life. ( Unless you get absurd with like 80 psi )

#3 I'll get you resources if you wish, but every tire manufacturer, and even State Patrol officers will tell you more tire pressure is better. We're talking a bump of 10-15 psi, not something extreme. Ford says to put 35psi in the tires of police cruisers. Most police and highway patrol departments put 50psi in police cruiser tires, giving them better performance at high speed, better traction on wet roads, and longer tire life... something important when you have to replace tires on 100's of vehicles.

#4 Ford recommends a tire pressure in the middle of the safe range. A balanced "middle ground" of soft comfort and better performance when stiffer. The "safe" range of your Ford tires is 25 psi to 45 psi. The manufacturer of the tires on your Ford/Mercury recommends 44psi max.
I have had all 4 of my tires at 44psi for the last 30,000 miles.

#5 "new" tires on the Ford/Mercury Hybrid have 9mm of tread depth. I just measured my tires last week and I have 6mm of tread left after a total of 39,000 miles. Plus I have 100% even wear across the entire width of the tire. ( I'll take photos of my tires and odometer if you wish. ) At 44psi my tires will last past 80,000 miles. At 35psi, some people have already needed to change tires at about 60,000 miles.

#6 softer tires, even those at 35psi will wear quicker at the corners ( edges ) of the tires, than in the center of the width. And the front tires will wear more from cornering, which is why you should rotate the tires.

#7 if you don't mind a slightly bumpier ride, there are really no negatives to putting 44psi in your tires, and at least a dozen benefits in addition to more miles per gallon. Part of the hybrid culture is learning to "coast" without the gas engine on. More air in the tires increases coasting distance dramatically.

#8 any good (honest) dealer or mechanic will tell you the same as what I did.

-John

 

I see rubber technology, like many others, has crept up on my dad.
I'll go for a test run in town to see about the road feel. I am starting to slio into neutral on hills and without an instant read mileage gauge it's not helpful but obviously, driving usng very little gas improves mileage overall.
Thanks, John.