How to increase efficiency?

[euromodder]

Originally Posted by toc

I understand for peak efficiency, the engine first must get to normal operating temperature. This in short trips would likely take around 1kM to do - so by the time it's got into operating range, the car travels around another 1kM before being turned off, and then does the same back.

I've never seen my car(s) warm up in only 1 or 2 km, not even in summer.

On those short trips, you'll almost always be in the less efficient warming up phase.
Warm air intake and engine / coolant / oil heater(s) may help it warm up faster. Soms folks in cold climates have their engine bay isolated.


Best alternative is using a bike - or bikes for everyone.
A moped is another option you might consider.
These days, you can get both with electric drive, or electric assist.

I want to know what I can do to reduce or remove fuel consumption over short trips.

You can basically do what most people here do:
change your driving style, pump up the tyres, add a grille block - and go through the hypermiling and driving efficiency tips to see what else can easily be done.

Aerodynamic modifications won't help much as your speed is low while aerodynamic improvements will best show at speed.

I've only lightly considered an electric conversion

With those short distances, you probably don't do many km either over the year ?
If so, an electric conversion will never pay for itself.

I generally hold the clutch in, and roll to the stops where possible, to save driving to the stop.

I prefer putting it in neutral.
That way I don't have to keep pushing on the clutch.

If you turn off the engine while coasting, you loose power steering (usually instantly) and braking assistance (usually after a few dabs on the pedal).

I'd really like to reach the 5L per 100KM mark so many have on this forum

You can always try, but I doubt you'll get there driving these short distances.
They're really killers for fuel efficiency.

[toc]

Thanks for the replies so far folks, all of them have given me new ideas.
Walking is ruled out, we are close enough to walk, but walking will be too tiring for the kids. For now anyway.

Electric conversion was really what I was thinking the replies would centre around - but the payback time being negative, well, I'll forget that idea!

Warm Air Intake I'll try and do this first. It seems to be the first that will help.
The car does have large front openings, the lower bumper has a large opening, and the front grill is open - I'll block those off in a manner that can be removed.

First things first though, I have to get my MPGuino finished installed and some data on coolant temperatures before and after to ensure I'm not cooking it.

Driving style was one of the first I started thinking of when I first came across this site (then I was lured to the MPGuino).
Since I thought more of that, pulse and glide has been predominantly what I've used where possible.

As to why I leave clutch in ? Pretty much cause I like to have control, ability to release the clutch have car already in gear was just a 'easy' thing. I should stop being so lazy.

Turning off and clutch starting I've started doing a little - but I would like to look more into whether this causes losses in start up / shut down.

The car also has a rear spoiler, I might look into whether that's a problem as well.

[Daox]

Unfortunately, from my testing warm air intakes do not effect warm up hardly at all. I'm sure they don't hurt, but its not a noticable difference. You'd be better off blocking your grill off and/or insulating the engine. I'm in a similar situation right now with a 7 mile (11km) commute and I will be insulating my engine soon, adding a block heater and I also have a full grill block.

[Ryland]

Originally Posted by toc

Electric conversion was really what I was thinking the replies would centre around - but the payback time being negative, well, I'll forget that idea!

I would suggest keeping an electric car in mind, either buying a used one or converting a gas car to electric because your current car is not going to last forever, at some point you will have to replace it, sure it might be a few years but why not replace it with an electric car at that point in time? I highly suggest checking out electric auto clubs in your area, see what they have for used vehicle listings, check online EV sales web sites, educate your self so when it comes time to buy a new car you have an idea of what your options are.

[bluejoey]

The majority of my trips are under 2 miles in length, yet decidedly bike-unfriendly where I live. As a result, I have lots of experience with this issue. Furthermore, I've got an automatic. The single most useful thing for me has been instrumentation. Beyond that, I've found DWL to be the best technique for me. I started out a P&G devotee, but my car loses speed too quickly when in neutral. In contrast, applying a light engine load and watching the instantaneous mpg and mph has brought me better results than P&G did, save when I was EOCing, which I no longer do since I'd like to keep this car for the next several years. Additionally, air up your tires. The single biggest mechanical mod I've made this winter has been the addition of a radiator block. I've got lots of bits of cardboard in front of the radiator, which significantly decreases my warmup times (as evidenced by decreases in instantaneous gallons per hour). So in shorthand...

1. Buy or build instrumentation
2. DWL
3. Air your tires
4. Radiator block

[bluejoey]

Furthermore, I've also experimented with a WAI and, while I do feel it has minor positive effects, I don't know if they're significant. I keep mine on because I think it helps. I might take it off again soon to compare, however. In contrast, the effects when I started blocking my radiator were immediately visible, so I'd recommend that first. Warming your engine is several times more conducive to efficiency than warming your intake air.

From the last two weeks, the three best and worst trip mpgs I've recorded are provided below alongside engine temps and intake temps to show what I mean. As you can see, there's a near linear relationship between engine temps and mpg, but a low correlation between intake temps and mpg.

39.7 -> 185, 51
39.1 -> 190, 52
38.6 -> 181, 63

22.8 -> 150, 50
25.6 ->172, 50
26.2 -> 171, 50

[toc]

Simple - Get sheet metal to block off the front openings.
Remove the air intake ducting.

That should theoretically do both, warm the engine faster by removing cold air to the radiator, and since there is no cold air flow from the front, the air intake with no ducting will be sucking in warm air (at the expense of making the filter dirty faster - nothing a good clean would not solve).

DWL I've just started, so as I climb the slight hill, I'll sit in 2nd gear up the street, which isn't too noisy (i.e. about 2500RPM).

Instrumentation is first on the list though, no changes are worth making without data to validate the effectiveness.

[euromodder]

Originally Posted by toc

Remove the air intake ducting.

Take into account that the intake ducting also serves to keep water out of the intake.

Depending on where the intake is located, and what climate you drive in, you want a circuitrous intake duct to keep the water out.

[SentraSE-R]

I did ABA testing on a WAI for my xB. Net results showed no difference in fuel economy. I keep it hooked up in the Winter, and have grill blocks, because logically they must help warm-up times. Even with both, my xB doesn't reach 59 degree C operating temperature until I'm 4 miles down the road, in 10 degree C ambient temperatures.

[TheMarkofPolo]

I'm in a similar boat as bluejoey, I have an automatic Vibe and a short commute to campus. I can bike to campus in 20 minutes, but my lungs can't take the cold air....no insurance to check that out.

Anywho, I have a permanent duct tape upper grille block. But for these short wintery trips, I have a removable lower grille block...a piece of garden molding jammed under the license plate frame and secured with duct tape. Simple, effective, and a tribute to Red Green.

The lower+upper grille block for short trips seemed to help warmup and help me stave off the awful winter FE blues.

(The lower grille did come off for long trips, though, otherwise the accessory fan came on, negating some fuel savings.)