Archives

Hey there. I was just looking online for ways to increase my gas mileage and ran across a link to this site. I figured I would joint up and learn a bit.

I don't have a very long drive to work each day (13 miles each way) but the problem is the hills. It's mountain road the whole time with next to no flat areas. I drive an 07' honda accord with the 5 spd. manual tranny. Im only getting about 32-36 m.p.g with the car right now. I know according to the window stickers on them and so-on that they were only rated for like 31 I know I can do better. The speed limit on the stretch of road is 65 m.p.h.. Have any tips for me? (and when I say hills people from kansas, like my wife, think they are mountains, lol)

Thanks a bunch,
Andrew

Welcome to CleanMPG, Andrew!

Depending on where you drive, I'd consider 10-20% under the EPA as par for the course - i.e. hypermiling yet getting under the EPA.

Welcome to cleanmpg. I live in Arizona and have done quite a bit of driving in the mountains of AZ and utah with my 05 Honda Accord and I usually get over 40mpg on those trips. With a manual transmission you should be able to get 40mpg easy. The trick is to take it slow going up hill and then let your car accelerate down hill. If it is steep enough you can experiment with coasting in neutral. Make sure to read

http://www.cleanmpg.com/forums/showthread.php?t=1510

This will teach you the basics and should get you started. If you don't feel comfortable with the more advanced techniques just start off with the basics and ease your way into the more advanced techniques. That is what I did. Although I haven't been able to get one yet a scanguage will help a lot with the instantaneous mpg readout and for some of the advanced techniques. 36mpg is already a good foundation to start especially on a hilly route, you should be able to get 40 easily.

good luck!

For me, the trick going uphill is when and how hard to accelerate.
Also trimming down your max speed uphill may help.
Without a scangauge, finding the optimum is tricky.
What works for me is to keep my acceleration light in the first 3 gears, then in 4th moderate (but not heavy) acceleration to desired speed. Then, find the lowest throttle setting that will just barely maintain my speed uphill. (in either 4th or 5th, depending on how steep the hill is)
Throughout this I always try to keep my rpm's under 3000, ideally under 2300.

You say the speed limit is 65.
Do you GO 65?
You'll find that most of us would treat 55 as their MAXIMUM speed on flat or uphill segments.

If you have a Scangauge, the LOD gauge is your friend here. Find a speed where you can maintain speed and about 75 lod up the hill in top gear. Higher speed/rpm and lower lod puts you into a less efficient mode of engine operation.

No, I don't go 65, I usually keep it at 55 unless I,m coming down the other side. And as for keeping it at 55 in 5th gear, it can't do it. Hills are too much for the cars engine to pull in 5th. It will keep it at about 60 but not less....high elevation kills the horsepower....but it also allows less fuel to be injected....great for the flat areas.

BTW, here's my suggestion for one conservative way to handle your commute:

1. Enter main road. Using lightest gas possible, accelerate to 55, shifting at 1800 RPM or earlier in each gear.
2. Traffic permitting, on uphill segments, use adequate gas to just barely go 50 MPH at top of hill.
3. After cresting hill, knock vehicle into neutral, release clutch, coast downhill.
4. Once downhill turns into level ground, depress clutch, shift into 5th, release clutch. Give vehicle light gas such that vehicle loses speed, getting down to 55 MPH on flat ground.
5. Repeat.

In step 4, I have you apply the gas just so your engine is doing a little bit of work rather than just idling along like a parasite while you're coasting down. If you had a Scangauge I'd suggest that you shoot for 20 horsepower or about 1.4 gallons per hour of fuel burn.

Many members of the community would actually do the following, which is a little edgier:

1. Enter main road. Using lightest gas possible, accelerate to 55, shifting at 1800 RPM or earlier in each gear.
2. Traffic permitting, on uphill segments, use adequate gas to just barely go 50 MPH at top of hill.
3. After cresting hill, knock vehicle into neutral, release clutch, shut off engine for a split second using ignition, immediately move ignition back to "Run" position, coast downhill.
4. Once downhill turns into level ground 'til speed drops to 55 MPH, depress clutch, shift into 5th, release clutch. Gas engine will start. Use throttle to maintain 55 MPH.
5. Repeat.

These directions presuppose a manual transmission and would be very, very dumb if you had an automatic.
Do not exceed either a safe speed nor the highest speed you can move without receiving a ticket on your stretch of road. If this is a problem, you may wish to consider simply leaving vehicle in 5th gear with no throttle during downhill segments.
If speed STILL over-runs, consider placing vehicle in 4th gear with no throttle during downhill segments.

There are probably another 12 valid techniques besides mine.
Have fun, and welcome aboard the board!

PS- Which powerplant do you have?

I have the 2.4L four cyl. with the 5 spd. manual.
The only thing I'm worried about is the wear on the clutch when popping it to start it and coasting in neutral. I'm just thinking that the price of a clutch (400$) ....would it pay off to cut the life of it down to gain the gas mileage in those 1/2-3/4 mile downhill areas?

I have the 2.4L four cyl. with the 5 spd. manual.
The only thing I'm worried about is the wear on the clutch when popping it to start it and coasting in neutral. I'm just thinking that the price of a clutch (400$) ....would it pay off to cut the life of it down to gain the gas mileage in those 1/2-3/4 mile downhill areas?

Once you learn how to do it, there should be no additional wear. I don't know the full extent, but Right lane cruiser, and Palemelanesian have been doing this for a while and have not had any issues, they should be able to shed some light on clutch life after multiple bumpstarts.

I wasn't too kind to my clutch early in its life, but it's still going strong. I started hypermiling at 150,000 miles, and now at 175,000 it feels as good as new. Here's my technique:

Shift into top gear, or 4th if you're at slow speed like 20 mph.
Let up the clutch pedal quickly, just to the point of engagement, then press back down on the pedal as soon as the engine catches. If you do this right, there will be no jolt or bump at all.
Choose your gear and clutch out like you do any normal shift.

26K on my Elantra and 25K on my Insight -- no issues with either. Both clutches are as strong as new.

To expand on the process laid out by Andrew, I let out the clutch pedal and then push back in immediately after contact. Imagine giving a spinning ball a quick and glancing blow to speed it up -- that's the idea you want to keep in mind. You want just enough of an impulse to get the engine to just turn over and catch. Once it is running, rev match to your speed and correct gear, then shift as normal.

When done properly, you'll actually have less clutch slip than starting from a complete stop. There is more wear at highway speeds simply because of the larger difference in rotational speed between the wheels and the stopped engine, but it can still be done smoothly with a minimum of slip.

You two are something else :p.

I feel like I have the bat signal or something.

I love hills. I've driven the 3 mile drive to my wife's office getting 36 mpg in my SE-R, on a cold engine, because I can coast the last 1.5 miles down one hill and up another. Then I've got the elevation to get some great mileage on the way home via a flatlad alternate route. I've pushed my mileage well into the 50s on the round trip with my Scion.