Hypermiling on my '00 Altima

[methodmix]

As gas prices are not expected to drop anytime soon, the concept of "hypermiling" has become a concept that many, including myself, are starting to embrace. Rather than testing out various gadgets and gizmos that promise to improve fuel economy (hereafter, FE), hypermilers improve their FE through simply changing their driving habits and using a little common sense. However, some take it to the extreme and go that extra mile to get every little last possible mile per drop of gasoline. Refer to the following article for a brief intro to hypermiling: http://www.edmunds.com/advice/fuelec...0/article.html. A more comprehensive website and excellent forum can be found at: www.cleanmpg.com.

The reason I'm posting this forum is because I've applied some basic hypermiling techniques to my '00 Altima and with interesting results thus far. Such techniques include: maxing out my tire pressure (44 psi, max recommended on my type of tire) on all 4 tires, AC off with windows only partially down (to minimize drag), warming up the engine for several minutes before driving, shutting off engine at long lights, pulsing (accelerating) and gliding in neutral (engine is still on), moderate and non-aggressive acceleration from a dead stop, and gliding in gear to avoid using brakes excessively. Thus far, I've only attempted these techniques for city driving (speeds range from 25 to 50 mph). So far, I've gone ~105 miles on the first quarter tank of gas (an improvement by about 30 miles!); I don't normally achieve this sort of FE unless I'm driving at highway speeds (>65 mph). I'm pretty impressed so far. I'm also using all synthetic 10w-30 mobile 1 oil and a k&n drop in filter; both of these have been incorporated for about a year now, so that in itself doesn't account for the near 30% FE improvement in city driving.

I'm just curious if any other Altima drivers have noticed similar results or if any of you have even attempted hypermiling at all. I will continue to drive this way until my next re-fuel (~1/4 tank remaining) and update you with my exact FE. If you have any questions or comments, I would love to read them!

Cheers.

Dave

[methodmix]

So I just refilled my tank after about 253 miles of purely city driving. I was down to almost 1/4 of a tank before refilling, and it took exactly 10 gallons to top it off. That's an average MPG of 25.3. This is 5.3 extra MPG than the EPA estimate! A 26.5% increase! With what I payed at the pump today ($2.97/gal Regular unleaded) I saved myself $7.87, when comparing to what the EPA MPG estimate would hypothetically yield. This is very encouraging, especially since all I did was boost my tire pressure and change my driving habits. I'll keep everyone posted on how my next tank turns out. FYI, I used BP/Ammoco fuel on the last test, which may have accounted for a slightly higher MPG efficiency. I am using BP/Ammoco again for this next trial. Normally, I use cheaper fuels, but from what I've been reading, these can hurt engine performance and FE. It's also worth noting that my city driving consists of about 7 lights and two stop signs when travelling to/from work (total roundtrip distance is ~13 miles); I also commute up and down hilly terrain for about 75% of the drive.

[methodmix]

I just want to add here that I checked my tire pressure after I posted my last thread, and noticed that my tire pressure dropped by about 2-4 psi per tire. This is due to the colder ambient temperatures being felt as the fall season is progressing into winter. So I decided to bump up my tire pressure to 50 psi, just to account for even colder ambient temperature that may likely affect my tire pressure in the near future. From what I've been reading, most tire manufacturers design their tires to handle up to (and in some cases above) 15% beyond the sidewall recommended pressure. This is quite believable since highway speeds can easily bring tire pressure up to this threshold. Since I am only traveling at city speeds (30-45 mph) and short distances, I think I should be ok here. In case anyone is curious, I am running Michelin Hydroedge tires, which I'm pretty confident will hold up to the added 6 psi. I do expect a slight increase in my MPG, yet cooler ambient temperatures may slightly offset this as it will take more time for my engine to heat up to proper operating temperature.

[JudoJohn]

interesting ideas. i always run my tires at max psi. have for years. however, i have never owned a tire that called for more than 36 PSI. as far as wariming up youor engine, just drive. that warms it up faster, and uses less gas. and keep your windows all the way up while driving on the highway.

BMW did some really good tests on FE and driving. they found that if yoou accelerate up to your cruise speed as quickly as possible, you get FE. so, instead of driving like a grandma from the stop light, give it some gas, and get up to your cruise speed (40 in town, 65-75 Hwy). when you get on the highway, don't drive like an old man, stick your foot into it. of course, ease off when you get to cruise.

I have a Sentra and I get in the area of 35-37 MPG on the highway. And i drive highway a lot. i set my cruise control at 70-75 MPH.

[methodmix]

Originally Posted by JudoJohn

BMW did some really good tests on FE and driving. they found that if yoou accelerate up to your cruise speed as quickly as possible, you get FE. so, instead of driving like a grandma from the stop light, give it some gas, and get up to your cruise speed (40 in town, 65-75 Hwy). when you get on the highway, don't drive like an old man, stick your foot into it. of course, ease off when you get to cruise.

That's a really interesting find! Do you have the link for that article? I'm curious to know how this test was performed, such as how long the cruise speed was maintained before having to approach a stop sign or a red light. Also, are they assuming an already warm engine when they do their tests? Putting it simply, this contradicts many findings (including my own ) when it comes to city driving (refer to www.cleanmpg.com), but this may be true for highway driving, where cruising speed is maintained over a longer time and distance, thus cancelling out the negative FE impacts of full throttle acceleration.

Thanks for your reply!

[JudoJohn]

i read the article in Road & TRack. hard copy, not on line. maybe you could check their archives.

it works for me. i did not say to smoke the tires off the line. it doesn't have to be "full throttle". Just get up to speed quickly. the quicker you get into high gear, the better. that is the point, IMHO.

[methodmix]

I cannot locate the article online, so I'll take your word for it. Bottom line, every car is different (i.e. different gear ratios, axle ratios, compression ratios, air/fuel mixing ratios, cam timing, etc...). That being said, each car has it's own "sweet spot" when it comes to ideal acceleration for best FE. The test that BMW did may be correct for most BMW's overall, but those engines are 'generally' designed for high output performance (unlike our fuel-sipping 4-cylinder Nissans ). In general, I believe you are correct, that brisk (but not full-throttle) acceleration produces the best FE under the right conditions (e.g. warm engine, relatively long cruise distance, relatively flat or downslope roads), which allows you to reach the highest gear (translating to minimal resistance from engine braking) in a short amount of time. Since every car is different, I recommend that you (and also myself) purchase a Scangauge OBD II real-time diagnostic monitor. This will tell you your FE in real-time, allowing you to fine-tune your acceleration to the most fuel efficient throttle depression, at any speed. You mentioned in an earlier thread that you get 35-37 mpg in your Nissan Sentra when cruising at 70-75 mph. I think if you go a little slower (to reduce wind drag and take advantage of wind currents from passing vehicles), you may see 40+ mpg! Try going about 60-65 mph on the highway for a full tank and see what you get!

[methodmix]

Just an update on my latest mileage.
City Average: 23.3 mpg.
Highway Average: 34.2 mpg.

The city FE average is a bit lower (by 2 mpg) than my last run. The highway mileage was my first attempt with hypermiling techniques. A second highway run will be added next week after I head back home from Thanksgiving.

[methodmix]

Originally Posted by methodmix

Just an update on my latest mileage.
City Average: 23.3 mpg.
Highway Average: 34.2 mpg.

The city FE average is a bit lower (by 2 mpg) than my last run. The highway mileage was my first attempt with hypermiling techniques. A second highway run will be added next week after I head back home from Thanksgiving.

I would just like to add, that for the highway mileage run, I added Techron Fuel System cleaner just before I topped of my tank before my trip. I assume that this added a certain percentage to my FE. Additionally, I dropped max speed to 65 (to minimize the effects of wind drag) and performed the DWL (driving with load) technique, which is basically driving with continual pressure on the accelerator pedal, but without adding more pressure on the uphill climb; this reduced my speed in some cases to 50 mph on the uphill climbs. Windows were fully closed for most of the drive and AC was off (but fan was running). Occasionally, I would draft an 18-wheeler for 5-10 miles at a safe distance of two seconds (~191 feet at 65 mph). I probably could have achieved higher FE if I hadn't have lowered my tire pressure from 50 to 45 psi (max recommended is 44 psi for my specific tire model); the lowered tire pressure was purely for safety at highway speeds. I will attempt the same techniques on my return trip and post my results shortly thereafter. Safe travels everyone!

[methodmix]

So I successfully made it back home after Thanksgiving travels! After my last tank refill, I achieved 31.62 mpg, which consisted of approximately 1/4 city and 3/4 highway driving; not bad, considering the EPA estimate for city is 20 city and 28 highway, which should have theoretically yielded 26 mpg with the given highway/city combination. So, after averaging all of my past mpg estimates, I've been getting ~5.1 mpg over the EPA estimate on my Altima!

[vtec-e]

Hi methodmix. I have been hypermiling this past 6 months or so and am hooked! My fuel consumption went from 40mpg (irish) to 55-60mpg. thats the best i can do so far. I could drive slower to work but then it would take forever. Its a 50k trip each way so i need to keep a little speed up (90kph)
My tires are up to 44psi and i have the grille blocked with a 4"x4" hole to let some air to the rad. I'm going to fit an indicator light to the fan to see if its coming on excessively during cruise. I may need to open the hole some more. Incidentally, when i plugged out the fan to raise temps a little, and therefore efficiency, a warning light came on. Obviously it was to warn me that the cooling fan wasn't working but i keep an eye on temps anyway so its not as much of a problem. Is there a way of manually switching the fan on/off without bringing up this alarm?
Also, i'd love a scanguage but my 1992 civic won't take one. Either way, our govt is going to charge road tax based on emmissions. So my 4.6l/100k civic will cost 600 euro to tax every year! Which sucks because there are newer cars burning MORE fuel that have less emmissions and as a result, willcost less to tax. And, no, before you ask, the tax will be based on manufacturers figures, not measured on my particular car. So that rules out me trying to find a way to clean my emmissions. Yay for the govt!!
Lastly, where can i get some figures on traction versus tire pressure. I would like some graphs representing different weather conditions, braking distance etc. Its proving very hard to find!

[InnerDragon103]

I use all these techniques while driving anyway -- I have a 94 Altima 5 speed. Manuals really do cut down on the consumption.

I do everything listed except turning off the engine at lights. LOL i find it strange they "invented" a new thing that's already been in practice and call it hyper-miling hehe... Like warp speed or something

[methodmix]

Hi, Glad to hear from a fellow hypermiler! You did point out something very interesting, that these techniques appear to be something new, but really are not that new. They created a lot of funny acronyms (e.g. FAS, DWL, P&G etc...) and technical terms, but the intention I think is to have a clear-cut definition when referring to such techniques to simplify the explanations for purposes of blogging and communicating to those who are new to this way of driving. My particular results are not unusual, as I'm sure you can verify. I don't have a manual transmission, but I can bet that I would do even better if I did.

You would be surprised by how much fuel you can save by shutting off your engine at lights! I try to go 1 step further and time the lights up ahead...for example, many lights I come to are when travelling downhill, so to take advantage of this kinetic energy, I shift to neutral and shut off my engine and coast to the light; but I usually only do this if I come to a light where I am familiar with the timing; I don't shut off my engine of the light is red for less than 1 minute. Now some people may argue that coasting in neutral with your engine shut off is bad for your transmission (because it requires constant lubrication and could overheat otherwise), but I only do this for a 1 mile or less gliding distance, so it should have a negligible impact.

What have you been averaging in city/highway driving?

Originally Posted by InnerDragon103

I use all these techniques while driving anyway -- I have a 94 Altima 5 speed. Manuals really do cut down on the consumption.

I do everything listed except turning off the engine at lights. LOL i find it strange they "invented" a new thing that's already been in practice and call it hyper-miling hehe... Like warp speed or something

[methodmix]

I just purchased a ScanGauge II OBD-II real-time diagnostic meter. I am awaiting shipment, but will re-post as soon as I test it out for myself. Cheers! opcorn:

[methodmix]

So I got the SGII and so far I love it!

Fuel Burn Rate @ Idle Speed (Gallons/Hour): 0.25 in Park/Neutral; 0.30 in Gear.

The above figures are likely to be true for other Altimas, but not sure. If you do the math, gliding with the foot off the gas pedal (equivalent to idle speed) and moving at 35 mph while still in gear will yield 116.7 mpg!

Another example would be driving with constant pressure on the gas pedal, say 1.25 gallons/hour. At this rate while maintaining a 35 mph speed you would average 28 mpg.

I will post more data as I get more time to test the scanguage. Here's my plan for testing (and this will apply to only flat road surfaces):
(1) Calculate fuel burn rate while maintaining 35 mph.
(2) Same as above for 40 mph.
(3) Same as above for 45 mph.
(4) Keep incrementing at every 5 mph until reaching 75 mph.

My hypothesis is that 60 mph will yield my ideal real-time fuel economy.

Cheers!