Improving highway FE?

[NoCO2]

Ok, so I just made the grim realization that my city mpg is about to overtake my highway mpg...I get 33mpg city and 36 highway these days....so I think I have the city FE driving down, now I need to work on the highway stuff. I'm going on a ~250 mile trip tomorrow and then another similarly distanced trip right after that and then another from there (going to be gone for the next week and a half, hopefully with internet still to check here while I'm gone).

How can I improve my highway FE? Basically all I have been doing lately is just setting the cruise control to 100km/h and just parking in the left lane with the windows up. I know cruise control isn't the best option so I'm going to make an attempt to keep my foot steady this trip and maintain throttle position rather then speed and see how it works. Also, if weather and traffic permit, I'm going to be trying some drafting/EOCing to see if that helps.

Any other tips you fellows can offer?

[Daox]

Its not unusual for hypermilers to get better city mileage than highway mileage. The wind resistance plus rolling resistance on the highway ends up keeping it lower. In the city, you really only deal with rolling resistance so there is a lot more area for gains.

Pulse and glide is the ultimate highway technique if you can pull it off, but its a lot of work in an automatic. Using driving with load if you can't pulse and glide is really your only alternative. Other than that, slowing down as much as possible to eliminate that wind resistance is going to net you good gains. If its not too windy out you can try to find a semi and stay 3 or so seconds behind it. This is good for a small gain and is still a safe distance behind the truck.

[NoCO2]

3 car lengths behind a semi is...(whips out mental calculator)...roughly 45 ft...so that puts me, still, well within the range in which a significant aerodynamic advantage will be noticed...sweet. According to mythbusters the aerodynamic drag begins to reduce at 100 ft and only gets better the closer you get, up until about 10 ft where you are having to modulate the pedal so much that your using more gas just trying to maintain distance which negates the effects and makes no closer then like...I think it was 30 ft, effective.

[SVOboy]

Aeromod that sucka,

[AndrewJ]

^ agreed

Aeromods beat technique on the highway any day.

I dunno about you, but P&G never did much for me on the highway. Aeromods, on the other hand, did plenty to boost my mileage, up to 55 from 49.

[Lazarus]

Originally Posted by NoCO2

3 car lengths behind a semi is...(whips out mental calculator)...roughly 45 ft...so that puts me, still, well within the range in which a significant aerodynamic advantage will be noticed...sweet. According to mythbusters the aerodynamic drag begins to reduce at 100 ft and only gets better the closer you get, up until about 10 ft where you are having to modulate the pedal so much that your using more gas just trying to maintain distance which negates the effects and makes no closer then like...I think it was 30 ft, effective.

The problem with trying to draft a semi besides the safety factor is that they are going to fast. Aero mod it x3

[thebrad]

Granted I was doing 55 mph, I feel monitoring the Throttle Position Sensor (TPS) readout and using the minimum amount necessary to maintain speed made a huge difference on the highway driving on my most recent tank.
It's time to fill up again and if my estimations are right, I should have hit ~55 mpg for the tank.

[tasdrouille]

I did 150 miles of highway yesterday going to Montreal. I started at 57 mph and went on my own for roughly 50 miles when a semi doing 65 passed me. I just stuck to him for the remaining 100 miles, far enough so I could always see his driver side mirror. I got exactly the same FE for both segments.

[NoCO2]

Thanks for the responses everyone. I figured, since most of the semis were going faster then I was, that the FE gains would be either negated or worse from the increase in speed even though I don't have as much wind resistance.

So, I got here and it took me just under 5 hours to do a normally 2 1/2 hour trip . The posted limit was 70mph (ouch) but traffic was light so I set the cruise control to hold me at the speed that got my RPMs to 2000RPMs and just left it there for the most part. I tried a little DWL but the route I took had VERY few hills so it didn't make a difference really then having cruise control on. I also found a semi doing just 60mph (i was doing around 57ish) and I noticed that on uphills he slowed down a bunch and on downhills he sped up a bunch...aka he was doing DWL stuff for his semi. So I hopped on in behind him so that I was more visible to cars coming up behind (at 80!) and I could keep the gas pedal steady with him and not cause any problems behind me.

I ended up getting about 34mpg on this tank which was mostly city driving, only the last half-ish was on the highway. The return tank will be the one to know how I'm doing on the highway.

Aeromods are coming, yes, I promise. However, I'm hesitant to do any until I get my scangauge because I don't want to just be doing aimless aeromods and not have any way to back-up my claims that they improve FE to people who ask.

[Daox]

Nice tank.