Fuel Efficiency and the Yaris

[Black Yaris]

Originally Posted by grampi

Over-inflating the tires definitely works however, I would take care not to exceed the max pressure listed on the sidewall for safety reasons.

It is extreemly dangerous to run your tires at a pressure higher then the manifacture reccomends, you run a high risk of tire seperation, expecially on the highway when tires are being heated up the most

[grampi]

Originally Posted by Black Yaris

It is extreemly dangerous to run your tires at a pressure higher then the manifacture reccomends, you run a high risk of tire seperation, expecially on the highway when tires are being heated up the most

I assume you're referring to the tire manufactuer?

[Black Yaris]

Originally Posted by grampi

I assume you're referring to the tire manufactuer?

yes

[palsan]

Does hypermiling save gas? Probably NOT!

Before you flame me let me explain ....

This past week I decided to try some of the techniques used by hypermilers to achieve their awsome FE. Even before I heard of hypermiling I was already trying to practice some of their techniques and two weeks ago I achieved the best FE to date (6.4L/100km).

What I did differently last week:
1. Slowed down in general, never above speed limit (kept to 100km/hr on highway and tried not to go above 2500 rpm).
2. Accelerate slower than usual (no revs above 1500rpm from full stop)
3. Brake slowly and steadily.
4. shift to neutral when possible (down hills, approaching red lights, and stop signs)
5. Avoided using A/C (even yesterday on way home when temp was 30c)
6. Below 40km/h until warm light goes out.
7. Looked for "face out parking" opportunities.

Observations:
1. By slowing down, accelerating slowly from stops, breaking slowly, and gliding to stops, you create much more space between you and the car ahead of you. This enrages many drivers behind you and they will hyper-rev their own vehicles to pass you. Result: hypermiler saves fuel BUT in order to pass you the other drivers USE MORE FUEL THAN YOU'VE SAVED. Therefore, unless a majority of drivers change their habits, a zero-sum game. Having said that, I will continue to do this but only when practical.

2. Avoiding the use of A/C is just not realistic. If people could do without A/C they would not purchase vehicles with this feature. I for one will try to use it only when the temp is unbearable.

3. Even something as simple as driving below 40km/h before the engine warms up is very difficult. In the morning coming out of my house drivers get visibly annoyed when I stay just below 40 - I'm not even out of my residential neighbourhood yet where the speed limit is 40! From my house the first stop is about 200m. I have observed drivers turning left, accelerating very fast to take a "short cut" just to avoid staying behind me. I then see them one or two cars ahead of me when I join the major street. Result: hypermiler saves fuel BUT in order to pass you the other drivers USE MORE FUEL THAN YOU'VE SAVED. Therefore, unless a majority of drivers change their habits, a zero-sum game.

4. Looking for "face out parking" opportunities probably cost me more fuel than was saved by not backing out of spaces. If you drive even a few metres to look for a "better" spot, you are probably using more total fuel. Better to take the closest space, go in front-first, and take advantage of your momentum.

5. I achieved 6.1L/100km -a savings of 0.3L/100km. That translates to 1.6L or $1.60 for the week! More on this at the conclusion.

Other comments on BailOut's recommendations:

Basic FE:
1) Slow down, and never speed
2) Accelerate and brake slowly and steadily
- see observation #1

3) Keep your tires inflated to at least the manufacturers recommendation, or as high as the maximum sidewall rating
- this one will actually save fuel but there is a limit. There is also a trade-off between fuel and comfort - most people will opt for comfort even if they have the discipline to check tire pressures on a regular basis.

4) Keep your vehicle properly tuned.
5) Use the smallest, lightest vehicle for the job.
6) Get the junk out of the trunk.
7) Run all your errands together,
8) The shortest route isn't always the best one.
9) When not in use remove the camper, bike rack, or any other addition that creates drag.
10) Never drive your vehicle hard before it warms up, and never idle it to warm it up.
11) Never rev the engine
- these do not affect other drivers' behaviour and will save fuel overall but require a major change in behaviour.

12) The realities of pumping fuel.
- good advice to buy fuel in the middle of the week. However, if more people did this the demand/supply equilibrium would shift and middle of the week would result in higher prices. The hypermiler can save on fuel costs but this is a zero-sum game.

13) "The Myth of Torque", or "Why you don't need 200bhp to pick the kids up and get groceries".
- absolutely true. The trade-off here is fuel savings vs. status/image. Many do not care if their high performance/heavy vehicle uses more gas - they wouldn't be caught dead driving an econobox. The reality - even for fuel economizers like myself - is that for a two car family, at least one of the cars will be a people hauling fuel hog. A family needs something like a mini van even though it will only be used for its intended purpose less than 10% of the time. The "soccer mom" will typically drive the majority of the vehicle's mileage by herself. The only way to get around this dilemma would be for people to have "econoboxes" to commute alone, and a stand alone "people hauler" - not economically possible.

Intermediate FE:
1) Never idle again, or "Never get ZERO MPG again".
- This implies turning off the engine. Problem here is that all other drivers EXPECT your car to be running. Therefore, regarless of what this may imply for the durability of your engine, it's not realistic to expect everyone to turn off their engines at stops. The split second it takes you to turn on the engine contributes to an even greater gap between vehicles leading to the scenario described in observation #1.

2) Going from "I can't drive 55" to "I never drive over 55".
- see observation #1 above

3) Take advantage of DFCO
- this only works best on manual transmissions - most cars are auto. Manual vs auto is a fuel economy vs convenience issue - convenience will always win!

4) Route planning based on known obstacles
- good advice!

5) Face-out parking & potential parking
- see observation #4

6) Use monitoring tools
- good advice here. However, a Scangauge costs about $160. Where I'm writting it would take saving about 160 litres of fuel to make up that expense. I can't see this saving you more than an additional 0.2L/100km. It would take 80,000Kms to break-even. Even though the financial cost/benefit is questionable I will probably end up getting one - we do live in a gadget econmy after all

7) Running tire pressures higher than the max sidewall rating.
- it may be "safe" but NOT PRACTICAL! who wants to drive around on 4 bricks?

8) The realities of fuels
9) The realities of fuel additives.
- ok

10) Modifying your vehicle for FE.
- cost of modifications will probably outweigh fuel savings.

11) Switch to synthetic oils.
- I've done this and it probably works to save fuel. However, if one stays on the same change schedule, the higher cost of the oil may outweigh the fuel savings. For this to lead to actual savings one needs to go beyond the 8000km between oil changes recommended by Toyota.

11) Fuel rebates.
- no savings here since it would require people to switch from other incentives for their current credit cards. For example, for me to take advantage of the rebates given by the oil companies around here (usually less than 1% equivalent) I would have to give up the 1% grocery rebate I get from my current mastercard.

Advanced FE
FAS
- by my understanding this requires turning off the engine - while it saves fuel - IS NOT PRACTICAL!
I don't care how much fuel it saves, my engine WILL NEVER BE OFF WHILE MY CAR IS MOVING! and I'm nearly as obsessive compulsive as the typical hypermiler! No one - but a small handful of individuals - will EVER go for this one.

P&G
DWL
DWB
- by my understanding these techiniques work only for hybrids - a tiny fraction of the vehicles on the road. Current technology makes the financials of owning a hybrid a losing proposition. The higher up-front cost, and the likely higher future maintenance costs (battery replacement for example) of buying a hybrid will not be recouped by savings in fuel.


Drafting
- very dangerous for the typical unskilled driver!

- Grill blocks & engine blankets
- the electricity to run the blankets may require the use of more energy resources than the resulting fuel savings.

- Leave Jack at home.
- may be illegal is some places.

- Advanced aerodynamics
- can only be done by the manufacturer before the vehicle is produced. To do it post-production may cost more than the fuel savings.

FINAL COMMENTS:
- While the hypermilers techniques may save fuel for the INDIVIDUAL hypermiler, it is very likely that the TOTAL amount of fuel used by ALL drivers may actually be HIGHER.

- in order to use less fuel across the whole economy there must be a drastic change is driving behaviour OR a drastic change in technology where all vehicles achieve the current FE of a stock Yaris.

Hypermiling is not a way to save the environment - its a SPORT. As such, it may be worth pursuing if it gives the participant a sense of accomplishment and pleasure. However, beyond the common sense techniques that drivers should know about anyway (and for whatever reason do not practice), hypermiling probably does not benefit society in general, and it may actually be detrimental as it leads other drivers to become more agravated thus taking this extra tension into their daily lives.

- I'm not sure if my savings of $1.60 for the week were worth the effort. Nevertheless, in order to pursue the SPORT I will try other techniques in the future. Up next, increase the tire pressure to 40psi and grow a thicker skin so that I'm not bothered when women give me the finger for gliding to a clear red light up ahead. Don't laugh that happened last week. It appears people rather maintain speed, break hard, and stand still at the light for two minutes than come to a slower stop and wait less than 10 seconds - go figure

That's the end of my rant. If you made it this far thank you for listening.

[Astroman]

That was a nice, objective post. It is only proper to look at the cons as well as the pros. Well done. Sometimes those techniques are not practical in certain situations. My route to and from work (before 8 and after 5) do not permit much of a chance to hypermile. The speed limit is 30mph, but most do 37-45mph so using DFCO on what little hills there are with that much traffic is pretty much impossible. I do shut the engine off at stoplights, but only if I'm not next for the light sequence, and usually turn the car back on about 10 sec. before my light will change so I don't have a Yukon pushing me into the intersection. Usually if I'm a couple of cars back and the light changes I have enough time to start the car back up and put it in gear before the cars in front of me have really started moving. But, say if its after 7pm, that same route leaves lots of room for using DFCO, or even shutting the engine off. I'm not worried about the legality of this because my Yaris is so quiet anyway. And as for leaving the jack at home that is perfectly legal in WA. In fact, you don't even need a windshield! But you do have to have wipers . Anyway, great objective writeup. Well written. I will continue to do what I can to reduce the thinning of my wallet. SUVs can suck my ass.

[randydandy]

Originally Posted by lovely09

The standard ways to improve fuel economy include not accelerating too quickly,planning your route so that you hit as few traffic lights as possible and not driving too fast.
I also live in the Philippines and yes,it is sometimes hard to achieve high gas mileage due to traffics mostly on rush hour.

im already very light footed. but max i can get for city driving is 10.7 km/l (30.28mpg) and 18 km/l (51 mpg) for highway driving

[knowmercy]

BailOut, I can't help but ask when's the last time you tore down an engine? You seem to know quite a bit about how they work and how to get the best fuel mileage.

[Truwriter]

Lots of really technical talk about mpg here but I only know that I got on the interstate to visit son, traveled in Ohio (I77 to OH Turnpike and west) and had the cruise on almost the whole time (toll booths). When I arrived I gassed up and did my math and got well over 45 mpgs. I have a 4 door sedan, 2008, automatic and could not be more pleased. Vehicle is comfortable as well. The Yaris is fantastic.

[palsan]

One other point on hypermiling:

"Hypermiler is a term coined by Wayne Gerdes to describe a driver who strives to exceed their vehicle's EPA fuel economy rating."

The EPA ratings - however flawed their methodology - are not achieved by: turning the engine off while the vehicle is moving, taking the jacks out of the trunk, coasting in neutral, drafting behind large trucks, etc.

Beating the EPA ratings - however noble - is not a fair game. Its like running a race where your opponent has to run 100m and you only run 80m, or playing a basketball game using an extra player and your opponent's basket being 20% bigger than yours.

The answer to the fuel "crisis" is NOT using vehicles in ways they were not designed to be used, making them potentially dangerous (hypermiling), BUT utilizing more efficient engines and USING THEM THE WAY THEY WERE DESIGNED TO BE USED.