How far can you go on...

How far can you go on a full tank? Most of us think weò€™re lucky to get more than 300 miles from a single fill-up ò€“ but thatò€™s not enough to satisfy Volvo.

The firm has added two more models to its eco-branded DRIVe line-up, the S80 saloon and V70 estate. The former has a theoretical range of more than 880 miles on one tank ò€“ not bad for a big executive.

Armed with that information, bosses challenged Auto Express to drive from the marqueò€™s HQ in Marlow, Bucks, to Milan in northern Italy. We grabbed a set of keys to see how far we could getò€¦

Downloaded directions from the Web had us reaching for our calculators. It seemed that even if we hit the Volvoò€™s combined economy of 57.7mpg, weò€™d still be running on fumes by the time we reached our destination. And if we were to encounter heavy traffic en route to the cityò€™s Malpensa airport, we might not even catch our flight home at all!

Some ground rules were required. So, while we stopped short of taping up the gaps between the body panels to improve the S80ò€™s aerodynamics, myself and my co-driver ò€“ photographer Matt Vosper ò€“ came up with four golden must-dos. Firstly, the power-sapping air-con was to remain off, as it harms economy. Secondly, the job of maintaining a steady speed would be entrusted to the S80ò€™s cruise control. The third rule was to limit ourselves to 65mph, which would allow us to avoid mixing with the lorries in the inside lane without losing too much energy or time ò€“ after all, we had a flight back to the UK to catch. Finally, we planned to drive as smoothly as possible and keep braking on the long motorway journey to an absolute minimum.

With these rules established, we nosed out of Volvoò€™s car park in Marlow and headed to the southbound M25 with our fingers crossed for free-flowing traffic. However, the early signs were worrying. Trip computers are notoriously optimistic, but for once we had reason to pray that our S80ò€™s was inaccurate. The estimated range of the fully brimmed saloon left us doubting our maths ò€“ because it said weò€™d run out of diesel in fewer than 300 miles!

This figure was calculated based on the carò€™s previous consumption: the Volvo had clearly been driven by someone with a heavy right foot. As we racked up the miles on the way to the Channel Tunnel, though, the display gradually increased, and by the time we caught our train it was reading nearly 1,000 miles. By mid-afternoon weò€™d covered more than 250 of those ò€“ and the estimated range of 815 in the tank showed that our economy-boosting methods were clearly doing the trick. Our overnight stop in the city of Metz, in eastern France, marked the halfway point in distance, yet we had more than half a tank of diesel left.

We were feeling confident. And despite our passage across the Alps into Italy promising to be far more challenging than the flat expanses of northern France weò€™d covered so far, morale was high. Cabin temperatures had been comfortable, too, despite the self-imposed lack of air-con. Meanwhile, the temptation to floor the accelerator was being tempered by an overwhelming desire to see the highest possible economy read-out on the dash.

As anticipated, day two brought steep inclines and heavier fuel consumption, although our route avoided Alpine passes and hairpin bends. Instead, we took the less dramatic but more eco-friendly 10-mile Gotthard Tunnel.

A few photography stops had put us behind schedule, though, and with only an hour left to catch our flight, we were forced to pick up the pace. We neednò€™t have worried, however, because as we arrived at the airport we were amazed to find we could have gone much further.

The trip computer claimed we had enough fuel to drive another 200 miles, and after brimming the tank we calculated our consumption. Weò€™d averaged 65.6mpg over 810 miles ò€“ exceeding the carò€™s official combined figure in the process.

It wasnò€™t only the S80 that was in a fit state, either: we could have carried on, too. Thanks to incredibly comfortable seats we had no aches after two days ò€˜in the saddleò€™. So Volvo, how about going even further next time? With a realistic range of around 1,000 miles, Marlow to Monza would be even betterò€¦