Volkswagen's one-litre challenge

The brief was simple: take Polo 66TDI Comfortline (diesel) as far as you can on a solitary litre of fuel.

It sounds simple enough, but if you're the type who gets anxious at the sight of the fuel light, then having the car drained of fuel before your eyes and subsequently filled with a precise quantity of diesel just might be a little nerve racking.

With the tank sealed, we were instructed to follow a set course over a series of rural roads in the gorges north of the airfield. The route was to take us through busy airport intersections before joining the 100km/h posted Sunbury Road to Bulla. From here, we were to head due north to Wildwood before doubling back on the Konagaderra Road to Oaklands Junction -- approximately a 40-kilometre course.

The engine remained off to the last possible moment, the thumbs came up -- and on a cold start I joined the busy Tuesday morning traffic. Fortunately, timing was on my side and a clean run through the lights allowed a steady pedal in building speed on to the freeway. Knowing that even moderate acceleration would harm my chances I was glad to have no one in my rear-view mirror.

That situation was repeated when joining the usually busy 100km/h road that borders Melbourne Airport, with barely a car in sight. This allowed me to sit on about 80km/h saving precious fuel without annoying fellow road users. In what felt like forever, I made it to the turn-off where it was time to find Polo's 'sweet spot' and really stretch its range. Having already ensured the windows were up and all the ancillaries were switch off (especially the AC) fuel economy was now determined by careful throttle application, gear selection, and optimum engine speed.

On flat ground the formula seemed to dictate that 1150rpm in fourth gear was a comfortable combination for ideal economy. Travelling at about 60km/h this also meant I wasn't too much of a hazard to the occasional driver approaching from behind in the 80km/h zone. Pulling over to let other vehicles pass was certain to eat into my economy.

Luckily, other cars out here are few and far between, leaving the steep inclines encountered as my only real challenge. Again, timing was on my side and having no other traffic to contend with meant I could pick a low gear and crawl up the hill on Polo's strong turbodiesel torque curve (Polo 66TDI makes 230Nm between 1750 and 2500rpm and 66kW at 4200rpm).

By now I had passed the 25-kilometre marker, which came as a pleasant surprise. Before leaving I'd guesstimated that given the Polo's combined consumption figure of 4.6L/100km, and knowing the terrain, I'd achieve between 23 and 25 kays.

Battling more long straights we eventually came to a long downhill section heading towards Deep Creek. In neutral the Polo coasted down the hill, saving precious drops for the climb at the other side... and what a climb!

When you're running on what must be vapour, this hill felt like it went forever, and what's worse was that by the time I'd cleared it, another lay ahead. Surely this was it.

Clearing the hill another long descent saw precious hundreds of metres add to my tally as the 30-kilometre market passed, and soon enough 35.
Chugging through roundabouts and back toward Bulla (Somerton Road) I was convinced I was done for when Polo stalled as I made a left hand turn back on to Wildwood Road. Dropping the clutch the little oiler fired back to life for an extra 300-metres before finally spitting the dummy.

With not a car in sight I waited until the speed dropped below 10km/h and opened the door to push Polo as far as I could with the ignition on, determined to beat my colleagues from rival publications (and knowing every kilometre meant a $10 donation to Queensland's flood appeal). At 39.7km, both myself and Polo were spent.

Now sure, the exercise in itself may not be completely germane, I mean you're not exactly going to try and repeat this type of drill on a regular basis, but it does show that with some basic know-how, extracting the most from your tank can yield substantial benefit.

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