Help me save Fuel !

If you want to reduce brake wear, engine braking is better than going into neutral. We live on a hill, and I use 2nd gear in our automatic when descending to reduce pressure on the brakes. I also use it for gentle engine braking in some other situations. (You don't want to overdo it in an automatic).

Notwithstanding a car culture that wants a new one every 3-5 years, we plan to own ours more like 10-12, so I do what I can to preserve major components, including transmission. Even if you do trade in, someone else will be buying your old car, so it helps the earth to preserve the transmission, etc.

You can protect your transmission in a couple of ways. One is to back into your driveway or parking spaces (or get a drive-through space). That way, when you re-start your car and the engine & transmission are cold, you don't have to shift into and out of reverse before shifting into drive. The less shifting you do with a cold tranny, the better. (Instead, you are reversing at the end of your previous trip, while everything is warmed up.)

If I am at a red light and won't be there long enough to turn off the engine, I put it in neutral. This causes less tranny wear than if you are in drive with your foot on the brake. (This applies only to automatic). If you are idling in drive, the tranny is always trying to push the engine, then backing off, then trying, then backing off, causing wear.

Turning off the engine when others would idle is very useful - I do this any time I can, even at red lights where I know it will be 10 seconds or more before I go. Not only does idling waste fuel, it is hard on your engine - incomplete combustion means more corrosive chemicals are created in the engine. You cause less wear to your engine re-starting it hot than you cause idling for 20-30 seconds. In a properly-maintained engine, most wear is caused by starting, idling, and short trips. One short trip causes more engine wear than hundreds of miles of steady highway driving.

Erich Jacoby-Hawkins
Barrie, ON

The views I express on this blog are purely my own and should not be construed to represent the official position of the Green Party of Canada - the same goes for all other people's posts & comments.

I am sorry, but I remain deeply skeptical of your 'plugging' driving style, for a couple of reasons:

1) it is contrary to every article I have read in the past 5 years about improving fuel economy through driving style

2) it contradicts my (admittedly rusty) understanding of physics and mechanics.

Physics: Energy used to travel increases by a square of velocity, so the time you spend driving faster than 100 km/h uses more fuel than the amount you spend driving slower than 100 km/h - averaged together, they add up to more than you would use at a constant 100 km/h. Moreso, accelerating is the main consumer of energy - once at a constant speed, you are only overcoming friction and wind resistance.

However, this is not a simple calculation, as a car moving very slowly is rather inefficient. Most engines are probably most fuel efficient somewhere in the 60-80 km/h range.

Mechanics: there seems to be an urban myth that taking your foot off the accelerator means you are using NO gas; actually, engines have a set minimum idle and even when coasting in neutral, there is some gas being injected. (If not, your engine would come to a full stop after not using the gas pedal for a while).

Now, I know that you have compared mileage on different occasions and this has indicated some savings from 'plugging'. However, such a comparison requires that ALL other variables be held constant; this includes the weight of driver and passengers, weight of luggage (including fuel), condition of road, and inflation pressure of tires. Most important (especially in a smart) is wind speed and direction; temperature/humidity/barometer can also affect wind resistance, I imagine. Comparison could only be valid using exactly the same route & direction (most trips involve a net change in altitude, and are thus 'uphill' or 'downhill'). Even controlling for all that, traffic can affect things - how often one must slow down, pass, or change lanes affects mileage.

I don't know how accurate your Scan Guage will be on a minute-by-minute basis. Hybrid & electric cars, however, often feature a battery capacity indicator which drops precipitously when you accelerate but only very slowly when you keep constant speed (and goes up as you decelerate if you have regenerative braking). This seems to prove that the accelerate function uses more energy than coasting.

Where did you hear of this method and the term 'plugging'? Was it from another person, or in some written or online source? If the latter, can you please provide the reference? Google hasn't turned up anything for me.

(On a purely non-scientific level, 'plugging' would seem quite annoying for the passenger and any drivers around you.)

Erich Jacoby-Hawkins
Barrie, ON

The views I express on this blog are purely my own and should not be construed to represent the official position of the Green Party of Canada - the same goes for all other people's posts & comments.

I eagerly anticipate a review of your experience with the guage - installation, operation, etc. I would very much like to have something more accurate than my fuel-tank needle and trip odometer combination. For one thing, now that I have switched to 100% biodiesel, I know my mileage is worse, but not by how much, nor can I separate it from the recent change in our driving patterns.

Erich Jacoby-Hawkins
Barrie, ON

The views I express on this blog are purely my own and should not be construed to represent the official position of the Green Party of Canada - the same goes for all other people's posts & comments.

Gareth Davies
Nanaimo-Alberni EDA
Parksville, BC

John, 100 kilometres = 62.14 miles and 2.81 litres = 0.74 US gallons or 0.62 UK gallons.

Using the US gallon we get 62.14 ÷ 0.74 = 84 mpg

Using the UK gallon we get 62.14 ÷ 0.62 = 100.2 mpg

I guess we were both inaccurate (not wrong), but in any event, the rate of fuel consumption is impressive.

: )

Cheers