“No,” she replied, “I have an extra maths lesson in one hour.”

“That’s fine,” I said, to my wife. “You run, and I will walk her to maths.” (1.8 km away)

“Walk?,” exclaimed my wife, “She doesn’t have time for that; she has tons of homework.”

If the humour of this conversation does not immediately occur to you, perhaps you should exercise your mind. Our culture has compartmentalized each aspect of our lives so completely that exercise is a specialized activity done purely for its own sake and worth the time it requires. Traveling to school, work, shops, friends or errands is a separate activity, to be done as quickly as possible, by car. Using a slower mode of transport is a waste of time, even if it involves exercise. But my calculations show that traveling more slowly actually saves me time, in two ways.

I jog for exercise and pleasure and cycle to get around and also for pleasure. It horrifies me to see people who will ride a bicycle all the way to the Magaliesburg on a Saturday morning for fun, get home, shower and hop in the car to get to the post office. I’ve seen this happen.

My longest regular ride is to a weekly voice lesson. It’s a 7.5 km trip by car that takes 15 minutes, or a cycle of anywhere from 25 to 35 minutes. On the morning of my voice lesson, I skip my usual one-hour jog, saving the same time that it will take me to cycle in both directions. Jogging and then driving would together take an hour and a half. Cycling takes one hour. 60 + (15 x 2) – (30 x 2) = 30. I save a half hour.

That’s not all I save. I don’t keep track, but I figure that sometime this year I will have made my hundredth cycle to my lesson. 100 x (7.5 x 2) = 1,500. That’s 1,500 kms of driving I have saved—farther than Johannesburg to Cape Town—and 150 litres of petrol worth well over a thousand rand. The environment has been spared more than 350 kg of carbon dioxide.

Let’s exercise our maths some more. A health study following more than 5,000 people over 40 years concluded that exercise equivalent to walking for 30 minutes a day for five days a week adds 1.3 to 1.5 years to your life.  Do those regular walks for 30 years, and you will spend 234,000 minutes walking, (30 x 5 x 52 x 30 = 234,000) but will have added 735,840 minutes to your life. (1.4 x 60 x 24 x 365 = 735,840.) So the averages tell me that the 20 minute stroll to her maths lesson added perhaps an hour to my daughter’s life. 735,840 ÷ 234,000 x 20 = 62.89. And, she later reported, “It was a pleasant walk.”

1 + 1 = 2.

I’ve made the process very simple for myself by creating an Excel spreadsheet that instantly calculates kilometres per litre and litres per 100 kilometres, with a running average for the last ten fill-ups. Now I’m making it simple for you, too, with a downloadable blank spreadsheet that has all of the formulas to make those calculations. All you have to do is reset your trip odometer at each fill-up, record the number of kilometres on the till slip—which already has the litres printed on it—and enter those two numbers on the spreadsheet.

To have your own copy of the spreadsheet, click on this link:

FuelEconomy

You should then be offered the option of opening it directly in Excel or saving it. Either option works, but if you choose to open it directly and then wish to save it—using Save As—you must be very careful to save it in the folder where you keep spreadsheets. It will not automatically opt for the My Documents folder.

After using it, if you’re not pleased with the fuel economy you see, try my 10 Unconventional Tips for Saving Petrol.

Note: FuelEconomy.xls was scanned with a fully updated version of Norton AntiVirus 2009 immediately before it was uploaded to GreenerHouse. No viruses or other security risks were found. That said, GreenerHouse promises not to take credit for your improved fuel economy if you promise not to make GreenerHouse responsible for any troubles with your computer or your spouse arising from the use of this file.