When drivers think of cars that are economical, French cars do not come to mind readily. But that may change with an unlikely pair of Renaults.

Earlier this month, Life took a newly launched Clio and a facelifted Fluence on a 1,500km road trip to Penang and Malacca.

The mission was to see how far they could go without refuelling and whether they match Renault's fuel economy claims.

The range test is vital because both diesel-powered Renaults need Euro 5 diesel, which is uncommon in Malaysia. Only the BHP chain of stations stock this grade of diesel and only in three areas: Johor, Malacca and the Klang Valley around Kuala Lumpur.

To make the test meaningful, two reporters and a photographer took turns to drive the cars as normal drivers would - the air-conditioner was kept running, the side mirrors were not folded in to reduce drag, the tyres were not over-inflated to lower rolling resistance and the luggage was not kept to a minimum.

The Fluence carried extra gears such as bottles of engine oil, a toolbox and a jerry can of diesel. A mechanic and an employee from Renault's local dealer, Wearnes, also went on the trip.

Both cars fared well in their range and fuel consumption.

After nine hours on the road, the Clio made the 725km journey from Renault's Leng Kee Road showroom to G Hotel in Penang's Gurney Drive with about two-fifths of its 45-litre fuel tank left. It covered 962km before the reserve warning light came on.

When it made its first refuelling stop at the Ulu Bernam R&R station in Selangor after leaving Penang for Malacca, the trip computer showed that it had travelled 991km on 45.5 litres of fuel and consumed 4.6 litres for every 100km, against the manufacturer's claim of 3.7 litres for every 100km.

The difference was likely due to the weight of the three adults in the car, the full luggage load, the car being caught in the crawling Georgetown city traffic in Penang and how the car was driven.

As soon as we got onto the North-South Highway at the start of the trip, we discovered that the Clio's cruising sweet spot is about 100kmh.

At that speed, the engine hovered at around 2,000rpm on its highest sixth gear. Above that speed, the engine speed climbed to as high as 3,000rpm at 130kmh and the trip computer showed fuel consumption spiking.

It took too much discipline to drive at 100kmh when the speed limit was mostly 110kmh, so we cruised slightly above the speed limit and the fuel consumption increased.

The Clio sprang two surprises. The first was that the right foot can beat the cruise control in saving fuel. When left on cruise control, the car maintained a gradual speed regardless of the gradient of the road. It accelerated when going uphill and slowed to its set speed when going downhill.

But without using cruise control, we could ease off the throttle and coax the car to coast downhill.

For the 991km that we drove before refuelling, about 99km - or 10 per cent of the distance - was driven without fuel consumption when the car was coasting.

After Cameron Highlands, I coasted the Clio downhill for almost 1.2km - the longest continuous stretch. It was a small feat.

The second surprise had nothing to do with driving. To help drivers and passengers fight boredom along endless stretches of highway, the car has a little-known feature that makes its engine sound like the power plants of a motorcycle or even a space ship. It was a largely useless yet oddly amusing feature.

The Fluence, which was the support car for the road trip, also fared well in its fuel consumption and range.

The sedan is powered by the same diesel engine as the Clio, but tuned to a higher output (110bhp versus 88bhp, 240Nm versus 220 Nm). It drove a staggering 1,234km - from Singapore to Penang and to Ayer Keroh on the outskirts of Malacca - before it had to be refuelled because of its larger 60-litre fuel tank.

The trip computer showed that it used 4.8 litres of fuel for every 100km, which is close enough to its official figure of 4.4 litres for every 100km.

Apart from fuel consumption, the long road trip also showed up the strengths and weaknesses of both cars.

The Clio aced in the narrow one- way streets of Penang's Georgetown. As we went hunting for the street art murals that Penang is known for, the hatchback squeezed into the tiniest spots and its abundant torque made city-driving effortless.

But its two cupholders between the front seats were insufficient for all the passengers and too small for anything larger than a standard 330ml aluminium drink can.

Also, the rear seats and headrests were set too uncomfortably upright for sleeping.

On the other hand, the Fluence shines with its legroom for passengers and space for luggage. Its 530-litre boot rivals that of the Mercedes-Benz E-class' 540-litre one.

But despite its latest facelift, the car looks somewhat dated. This six- year-old model is expected to be replaced next year.

At the end of the trip, the Clio and Fluence proved that diesel car owners need not worry about finding a suitable pump when venturing up north.

Most times, one full tank is enough for driving to Kuala Lumpur and back.