I had never considered myself a gas guzzler, leaving the family wagon at home on week days, and limiting my driving to work errands in small company fleet cars.
Yet there I was, motoring along with a leaden right hoof, seemingly unable to obey eco-driving guru Mark Whittaker's exhortations to "feather" down on the accelerator and ration the fuel I was squirting needlessly into the maw of the engine.
It was while trying to negotiate the undulations of Tamaki Drive towards the end of a 50-minute circuit that I began wishing I'd worn light bedroom slippers for this test of nerves.
Instead of accelerating downhill to raise enough speed to cruise to the top of the next rise for maximum fuel savings, I was losing momentum on the climbs and then over-compensating by pumping too hard on what Whittaker calls the "loud" pedal. That was a sheer waste of energy, recorded mercilessly by a dashboard computer display telling me I was burning fuel at rates which - if sustained - would have taken up to 30 litres to travel 100km.
Although those spikes were brief, if all too frequent, they compared with almost zero consumption when the engine was ticking along nicely in cruise mode with no throttle and sparing use of brakes. I managed only sporadically to get the Herald's 1400cc Hyundai i20 into that sweet spot, which former racing car mechanic and motor company service manager turned eco-driving coach Whittaker says is best attained by looking long into the distance - to judge exactly when to lift off from the throttle and cruise to a halt rather than dropping the anchor.
I took some satisfaction in finding I had eased the car's average fuel consumption from 8.9 litres/100km at the start, to 7.9 litres.
Whittaker said we could have got close to the Energy Efficiency and Conservation Authority's rating for the car of 6.8 km/100km if we had enjoyed a good run on the open road.