Phase I Complete: 18.8% Increase

[accord_minded]

Hi All-- It's great to be involved in this community!

So, I joined up a month or so ago after hearing about hypermiling from my brother. My situation is that I bought a 2004 Accord EX 4-cyl AT last December. Before that, we were a one-car family and since I had a 2.0 mile commute, I either walked or biked to work. Did that for 3 or 4 years and was feeling very virtuous.

Well, for many reasons I won't go in to, I am now faced with a 72 mile (EACH WAY) commute. So my commute just increased by, oh, 70 miles! On the good side is that it is almost all highway with little traffic. So, I don't have any stop-and-go stuff which would surely make it undoable. As it is, I can cover the 72 miles in either 65 minutes (without hypermiling) or 75 minutes (with hypermiling). With such a long commute I want to maximize my fuel efficiency. Also just want to do it with the car I have (2004 Accord) rather than get another car.

So I have a phased approach to improving fuel efficiency:

• Phase I is just learn the hypermiling techniques. The only addition to the car is a SCII just so I could learn how it works and get used to it.
• Phase II is to do the basic aero mods (air dam, lower grill block, upper grill block, passenger mirror delete, wheel covers, increase tire pressure). Also will get a vacuum gauge.
• Phase III is a Kammback and maybe some other more advanced mechanical changes.

So, the results are in for Phase I: Hypermiling.

Baseline:

• I have 2 baseline runs where I just drove normally with highway speeds (75-80 around here); liberal use of A/C; just driving as I used to drive. Tire pressure set to badge values 32F/30R.
• After two fill-ups, my baseline average MPG is 28.47.

Hypermiling:
After completing the baselines, I started hypermiling.

• What I'm doing: all the standard stuff, but no EOC (since my automatic transmission won't be happy with that). No A/C. Windows up. DWL, DWB, P&G, engine off while stopped, etc.
• Tires still at 32F/30R.
• After three fill-ups under hypermiling driving conditions, my average MPG is 33.82.
• That's a 5.35 MPG increase or 18.8%!

Plus I can easily get to 500 miles on a tank which is really pleasing.

I'm prepping all the mods for Phase II all at once and then will install them all on the same day and on a mostly empty tank. Once the mods are on, I'll fill up and start Phase II testing which will be hypermiling and basic aeromods.

So rather than the incremental approach of: install one aeromod, measure results; install second aeromod, measure results; etc., I'm going to go with the all-at-once approach.

My goal is to be able to get to 40MPG and 600 miles on a tank. So, I'll need to increase fuel efficiency by another 15.5%. Doable?

[elhigh]

Doable? Oh, yeah.

Check Istas' garage page for his '05 Accord. He's done some aggressive aero mods and is averaging well north of 40mpg per tank, banging in over 650 miles per tank sometimes. His record is over 680 miles and 48mpg. You could do as well.

[Daox]

Very nice job. I agree, 40 mpg is definitely doable. I look forward to seeing the mods!

[accord_minded]

Originally Posted by elhigh

Doable? Oh, yeah.

Check Istas' garage page for his '05 Accord. He's done some aggressive aero mods and is averaging well north of 40mpg per tank, banging in over 650 miles per tank sometimes. His record is over 680 miles and 48mpg. You could do as well.

I was following Istas and what he was up to and forgot to check his overall results. Thanks for the reminder...there's just too much good stuff here to remember it all!

[user removed]

Can you pick up a drafting partner, big rig or bus and let them push the air away for you, at say three stripes separation, about 130 feet? How does the Accord do shifting from neutral to drive while moving at speed? My Fiesta is good for close to 50 MPG pulse drafting a larger slower moving vehicle, even at 65 MPH. Sounds like your speed limit is 70 or more to do to do 72 miles in 65 minutes, close to a 70 average?

40 should be doable with a 31 highway rating but you need to find or create opportunities to coast, even if you pulse to 5 over on a deserted road and coast down any grade that extends your coast.

If thta commute is all you drive the car then 28 is not even epa highway. Local driving also?

regards
Mech

[whatmaycome14]

I bet with some slight aerodynamic modification you should be able to get upwards of 45mpg in the right conditions. Maybe not an entire tank, but certainly for a trip or two.

[accord_minded]

Originally Posted by Old Mechanic

Can you pick up a drafting partner, big rig or bus and let them push the air away for you, at say three stripes separation, about 130 feet? How does the Accord do shifting from neutral to drive while moving at speed? My Fiesta is good for close to 50 MPG pulse drafting a larger slower moving vehicle, even at 65 MPH. Sounds like your speed limit is 70 or more to do to do 72 miles in 65 minutes, close to a 70 average?

40 should be doable with a 31 highway rating but you need to find or create opportunities to coast, even if you pulse to 5 over on a deserted road and coast down any grade that extends your coast.

If thta commute is all you drive the car then 28 is not even epa highway. Local driving also?

regards
Mech

I had a rig in front of me this morning and stayed behind him for about 50 miles. Distance between me and him varied depending on what I was doing. Probably within 3 stripes at times, but generally a bit further back. Not too close to be dangerous, but probably not close enough to be very helpful.

The Accord doesn't seem to have any trouble shifting between a gear and neutral. I do either DFCO or coast in neutral depending on length and grade of hill and what else is going on around me. DFCO on the accord is pretty good, if it kicks off due to low RPMs, and I still have some downgrade left, I shift to neutral to keep the coast going.

I have mostly gentle rolling hills so I'm still learning how best to deal with them all. I've been driving with load going up, then pulsing near the top to get up to about 70MPH, then DFCO or coast in neutral down. I find that I'm still gaining a little MPH even at the very end of the commute.

I have mostly 70 MPH limits, but some 60s and one town with 4 lights midway through the commute. Prior to doing hypermiling, I was doing 75-80 MPH for large stretches of this commute which allowed for close to 60MPH average speeds. With hypermiling, I'm staying around 60MPH with 65-70 on pulses.

Probably about 80% commute/highway (maybe more) and the rest around town.

[kafer65]

I'm stoked for you, man. Totally doable. I'd scrutinize those tires. What brand and how old. Can you tolerate airing them up to within 10% of max? That would make a big difference on some tires. My brother picked up 3mpg highway ( in a small KIA SUV I think) airing up from somewhere where you are now. If they aren't LRR then use them up and plan for ones that work with you on your goal. Happy hunting!

[accord_minded]

Originally Posted by kafer65

I'm stoked for you, man. Totally doable. I'd scrutinize those tires. What brand and how old. Can you tolerate airing them up to within 10% of max? That would make a big difference on some tires. My brother picked up 3mpg highway ( in a small KIA SUV I think) airing up from somewhere where you are now. If they aren't LRR then use them up and plan for ones that work with you on your goal. Happy hunting!

So far, lots of support for 40MPG or more from you all. Thanks for the support! Motivated!

Can't remember the brand of tires, but they are as per manufacturers recommendations for this car. Tread is good. Phase II (aeromods) will include raising tire pressure. Sidewall says max is 44PSI. Will go to 42F/40R or maybe a bit more. I saw some data on here somewhere that showed diminishing FE gains and increasing road feel once you get up into the 40s and above...But there still seems to be some difference of opinion on tire pressure. Anyway, 42/40 oughta help quite a bit, right?

[user removed]

Avoid using DFCO if you can, coasting in neutral is much better at those high speeds. If you are going 60 and use .25 gal par hour idling, you are getting 240 MPG coasting. DFCO means you are using inertia to make that mileage infinite, but you will slow down much quicker than coasting.

If you are very familiar with the terrian, think of it as a roller coaster and where you can pulse and coast the longest or coast more total time. The tactic is dependent on the terrain. Coasting downhill with the engine idling is your goal. When the grades are very slight, pulsing uphill, not hard acceleration but very gradual (uphill) means you can coast downhill all the way to the bottom of the hill. If your downhill speed peak could get you a ticket then you want to reduce your top speed climbing the previous hill.

Think backwards from your top speed point. If your speed increases downhill then you want your peak speed to soon be gone coasting up the next hill and then when you get to the top of that next hill you don'y want to be going so fast that you overspeed on the next coast.

Like a roller coaster that climbs once then coasts through many hills curves and even loops, you want the ratio of pulses and glides to favor the glide, by as great a margin as possible. If you car is mechanically in good shape you should to easily beat highway EPA, but I think once you get to 40, you will hit the law of diminishing returns, however adjusting the "nut behind the wheel" will get you to 40% over EPA. Go 44 psi on your tires, and use the roller coaster strategy.

regards
Mech