I offered the MOTH (Man of the House) the opportunity toi contribute to this blog as we rumble along. As we still need to drive for employment purposes (there is the small matter of our mortgage and very little public transport in the large region we cover in our work), we have adopted the technique of hypermiling when driving. The MOTH has always been fond of numbers, and has taken to hypermiling like a duck to water. Below is his contribution for this month, on the delights of hypermiling along.

We have had a rather lengthy journey towards this six-month experiment with trying to live a lifestyle with a much-reduced carbon footprint.

About four years ago, when we began seriously considering a move out of the city and I became serious about looking for a different kind of job, we realised that we would need to purchase a car once we moved (and I lost the work-supplied car that I had enjoyed for the previous two decades).

After exploring options and considering various possibilities, we decided to purchase a hybrid, a car that ran on both petrol bought from the bowsers and electricity generated from the battery in the car. Not the upmarket option, the Prius, but the “poor man’s hybrid”, a Honda Insight.

We’ve been running this car for the past 42 months. It came with its very own Eco Assist^TM system, offering all sorts of hints, prompts, and rewards to encourage environmentally responsible driving (which may itself be an oxymoron, since every time we make a trip in a car we are adding to the pollution that is pumped into the environment and contributing to the degradation of the environment that is taking place all around us). 

In the early days, I had fun with the “eco” facilities that appeared on the little computer screen in the middle of the steering wheel. By driving carefully, not accelerating fact, and not speeding excessively, we were able to “win” first one flower (bit by bit – first the stem, then one set of leaves, then a second set, and finally the full three-leaved flower). Then, over the kilometres of the ensuing weeks, with continued careful driving, a second flower … and ultimately, a third flower. Hooray! We thought … we are careful drivers.

Then the next level of the system kicked in. Depending on how the car was being driven at the time, anywhere up to five small flowers would be sitting at the top of the little computer screen. Driving like a hoon, accelerating rapidly and braking suddenly, with air con on full speed and radio blasting, would see the number of flowers reduced to two, one, or even none. (Or so I am advised … I have not tested this empirically!)

At the other end of the scale, turning the air con off and not accelerating rapidly, would ensure that four, four-and-a-half, or even five flowers on the screen. But a minute or so of unthoughtful driving, and the number of flowers would start to reduce. An incentive, you see, to revert to cautious driving and to recapture the full five flowers.

To encourage the driver in this task, other options could be called up on the tiny computer screen in the centre of the steering wheel. One screen identified how far I might be able to drive on the amount of petrol left in the car. Another announced how long we had been driving since ignition. Another showed whether it was the petrol or the battery which was supplying the power at the particular moment. And so on …

Of course, this then raised the issue of safe driving … and my penchant for pushing the button and tracing through all the screens and seeing what they each had to offer. “Keep your eyes on the road”, “stop playing with your little computer”, were the injunctions that came from  … (well, someone else in the car, I guess … I was concentrating on the screen, I mean the road).

Three of the screens actually provide a collection of data that helps the driver to refine their driving practices and develop a more “eco” style. One screen identified the current amount of litres per 100 kilometres that was being consumed. It took the average over the distance from when the button was set at zero, and so provided a commentary on the driver’s habits during the current trip. Usually, trips around town would provide a measure of about 5.4 to 5.8 litres per 100 kms. On trips that had more short stop-start segments, the rate went up (more litres of petrol used). On trips with longer segments, the rate would decrease. Once or twice, I recall, I had dipped down to 5.2 l/100km.

On one occasion, when there appeared to be a problem with the transmission, I drove from Goulburn to Sydney on no more than 80 kph. On this trip, we dipped below 5.0 for a while. (And it turned out that the warning light was simply a warning that time was drawing near to have a service —  not a warning that something had actually gone wrong in the transmission. Phew!)

Another screen provided a short history of ltr/100km rates – the current trip, and the last three trips (each trip starting when the ignition is turned on). This meant I could look at the petrol rate on long trips on the motorway – 5.3, 5.2, sometimes 5.1 – as well as trips around town, short and sharp – 5.8, 6.2, even 7.5 (this was a drive from our house to a spot just a block away).

The third helpful screen showed the immediate rate of ltr/100km, second-by-second. This was the frightening one. Start up, push the accelerator, drive (slowly) onto the street – the rate was over 15ltr/100km. Drive for a kilometre, and the rate varied according to whether brake or accelerator was being pushed … and the overall rate would slowly lower. This screen was worth careful attention!

But all of this was a long, slow prelude, to the most recent aspect of our attempt to develop driving habits that were (relatively) environmentally friendly. (Or that should be, that lessened the environmental damage that I was doing with each trip in the car.)

Recently, we discovered HyperMiling. This is a phenomenon that has developed in the past 15 years, to foster energy-efficient driving. There are various elements to driving that effect fuel economy. Some factors are maintenance matters: tyre pressure, type of fuel used, etc. Other factors are under the control of the driver: choosing the right gear, braking carefully, coasting or gliding, accelerating at a regular rate rather than in short bursts, and anticipating the traffic ahead of you.

One factor that is of great significance is driving at the speed that provides the best economy of fuel (and by extension, thereby provides the least pollution into the air). Apparently the 2005 US Fuel Economy Guide declared that the optimum speed was between 50 and 55 mph (80 and 90 km/h). That is, travelling in the 80s would result in a better fuel economy, than travelling at higher speeds.

Elizabeth and I decided that we would do an experiment with our trips to Sydney in June and July. We were due to travel to Sydney, with our work, twice in June, and once in July. Travel along the motorway is relatively unimpeded, and we can motor along at the speed limit of 110kph for much of the 360 kms of this trip. Indeed, especially as we approach Sydney, we can go with the flow and find ourselves zooming along at 115kph, 120kph, or even more!

So in our Sydney trips, we travelled as was our custom – setting the cruise control for 110kph (or 110kph in designated areas) and only accelerating past this when overtaking. On some of the steeper hills, to save the engine, I would cut back to a slower speed until we hit the summit of the hill… but basically we followed the speed limits, along with many other motorists on the road.

The result? The first trip averaged 5.4ltr/100km, whilst the second trip averaged 5.6ltr/100km. Both of these figures were above the advertised “optimum performance” that the car’s manufacturer had provided, of 4.5ltr/100km on the “open road”.

Then, in July, we travelled the same trip, for the third time, but with the cruise control set at 90kph for the stretches on the motorway where the limit was 10 or 20 kph higher. This meant that we scarcely passed many cars – but that hundreds of cars sped past us at the speed limit (or higher, in many cases). Once again, on the steeper hills, we slowed … indeed, I tried to ensure that there was no excessive acceleration for the most part on these hills.

The results were quite striking. By travelling at no more than 90kph, we achieved an average of 4.4ltr/100km on the trip to Sydney, with the computer showing a stretch in the latter part of the trip when the reading dipped to 4.2, then 4.1, and (briefly) to 4.0ltr/100km. This was very exciting! A quick calculation indicated that, if this was the regular driving pattern, over the course of the year, not only would less pollution be spewed into the air, but somewhere around $250 would be saved in petrol costs.

The return trip was a rather different one, with less motorway time. It was a split trip, with overnight stays at Stockton (north of Newcastle) and the Stroud, meaning that we were on the M1 for much less of the overall trip. The readings were 5.4ltr/100km for the leg from Sydney to Stockton (we left Penrith at 4pm on Friday, so traversed 40km on Sydney traffic in the peak hour), and also 5.4ltr/100km on the leg that went from Stockton to Stroud to Gloucester and then to Wauchope.

The overall rate for the whole of this trip (totalling 1140km) was still 4.8ltr/100km, still a favourable comparison with the June trips (with readings of 5.4 and 5.6). So we are convinced of the benefits of HyperMiling. Better fuel economy. More intentional driving habits. And better environmental impact (just a little, but better than nothing).