‘Sixteen hundred kilometres, on one tank?’, the man at the petrol station counter smirked, handing me a folded VAT receipt. ‘Hope you’ve got breakdown cover ready – you’ve got no chance.’

I had a little more faith in the task ahead than he did, but not much. If fuel economy claims sound too good to be true, there’s frequently a reason for it, and on paper at least the refreshed Opel Insignia is nothing if not ambitious.

Its subtle design update last year tackled a number of D-sector criticisms head on. List prices came down, discounts were removed, new equipment made an appearance and, most importantly, the two most popular engines for fleets dipped under 100g/km for the first time.

At 3.7l/100km, the pair of 2.0-litre diesel engines are frugal enough to give the Insignia the longest range in its class without resorting to downsizing, hybrid technology, wacky wind tunnel design, or stripping equipment. You even get a full-size spare wheel in the boot.

In theory, that means you can fill the Insignia’s 70-litre tank and travel 1,892km before grinding to a fuel-starved halt.

Enough for us to travel from Vauxhall’s head of[1]ice in Luton, to sister brand Opel’s headquarters in Russelsheim, just outside Frankfurt, and arrive back at the start point with range to spare. Big news for a car which will do most of its work on the motorway. In theory.

In practice, though, it has to be able to do this without needing to hypermile. Time is a precious commodity for business drivers and a 90kph motorway trip is a good way to add unnecessary hours to the working day. So in the spirit of real world driving, we’d set the car the additional challenge of covering the return journey without modifications, without coasting downhill, slipstreaming or driving at abnormally low speeds.

Our car had come straight from Vauxhall’s business demonstrator fleet, and had spent the last 4,000km being run in at the hands of potential corporate customers up and down the UK. However, concern number one: the indicated range when brimmed was 1,100km, which if true would mean rolling gently and incongruously to a halt on an Autobahn verge somewhere on the way back. My only hope was that the computer was used to test drives being carried out at more pace than we were planning.

We filled the tank thoroughly in Luton and my lack of confidence was short-lived. Recent improvements to the Insignia’s aerodynamics were showing up in near non-existent wind noise, and the new 16-inch alloy wheels were smoothing the rougher bits of the British motorway network. With the Insignia refusing to break the 115kph limit I’d set, we’d reached the Channel Tunnel showing an indicated 3.9l/100km.

Coquelles brought the day’s second coffee, and five minutes to set the navigation for Russelsheim. The first section of the route through Belgium was to be vital. Against the undulations of the British motorways, the Belgian A10 highway casts a roughly surfaced but flat, straight route towards Brussels and the economy crept up further, reaching 3.8l/100km around Brugge and barely dipping as we crept through roadwork-induced traffic.

Sixth gear was the perfect tool for the job, and at 115kph just outside the peak torque, but with the still large capacity engine allowing it to waft along with barely any input from the turbocharger and no need to downshift.

We reached a rest point at Dutch-German border with the display reading 3.8l/100km, feeling relaxed but in need of caffeine and fresh air. Surely this was going to be easy, we laughed. We were to be proved wrong.

The Autobahns showed up just how slow our UK speed limit is compared to the rest of Europe. Crossing the border into the steep inclines of the Eifel mountains, our speed limiter meant thorough checks of the rear-view mirror to avoid being wiped out by the high speed convoy of German executive saloons in the outside lane, while the sun set behind us.

But it’s a safe and relaxing way to travel, highlighted by our third traffic jam of the day, caused by a BMW 3 Series spinning off the carriageway under heavy braking in the wet, barrelling onto its roof at the start of a section of roadworks.

Heading for home…

The Insignia rolled into Russelsheim at 10:30pm, with ache-free occupants keen for a rest after the hours of concentration. The Insignia tinked gently in the underground car park, showing just over a third of a tank was missing and an average of 3.9mpg over the first 779km. Enough to make the return journey look simple, even with a detour into Opel headquarters the following day.

A car park lined with Insignias awaited us at Adam Opel Haus the following morning. The company’s glass-and-metal clad headquarters form a small part of a site over half the area of Monaco, where its founder began building sewing machines in 1862, and almost 110,000 Insignias leave the factory here each year. A small hint of the importance Opel places on its flagship car.

I had a brief three hours to take in the facility and meet Opel fleet boss Ian Hucker, before beginning a time-conscious trip back to our scheduled Euro Tunnel crossing that evening. Driving steadily on the way over had made the journey a relaxed one, with no concerns about straying over unfamiliar speed limits or collecting fines. 

The return journey had a deadline, but with a little restraint we left feeling confident that we could get back to our start point.

Belgium had other ideas. With the clock ticking down to our train crossing, the Brussels ring road had choked on a combination of pre-rush hour traffic and an accident, and the Insignia’s navigation diverted us into the city centre. This was a gamble, and it didn’t pay off. We rolled into 90 minutes of gridlocked traffic, roadworks and every-driver-for-themselves aggressiveness that we couldn’t contend with while maintaining a steady right foot.

Frustrating, but we were powerless. No amount of aerodynamic upgrades, clever gearing or engine tuning can mask the damage done getting the Insignia’s bulk moving in bumper-to-bumper stopstart traffic. Short of pushing the car we were short of options other than simply watching hours of hard work ebb away.

By the time we reached a service station just outside the city, the all-important average consumption figure had lifted over 4.0l/100km for the first time and the weather was starting to turn. That valuable economy-boosting section through West Belgium and Northern France did us no favours either, the trees craning backwards in a strong headwind and the wipers roaring up and down the windscreen with the additional drag.

Unsurprisingly, our economy continued to slump all the way back to Coquelles. By the time we parked on the train, the gauge was showing 4.2l/100km – a disappointing place to be after such a promising start, but Luton was still within reach.

On the positive side, Brussels had pushed our repatriation back beyond the rush hour and the motorways were clear, even through the dreaded Dartford crossing. Without the headwind, our economy figure was beginning to climb again, and as we passed the M11 junction of the M25, the dashboard finally told us that we should be looking for a fuel station soon. We’d covered 1,500km.

I could sympathise. With eight hours of travel under my belt, refuelling was on my agenda too. The tiredness had started to materialise in clammy oxygen-starved palms, uncontrollable slow yawns and dry eyes that no amount of mineral water could cure. But, with over 160km of range left, the detour around the two closed M1 junctions into Luton didn’t become much of a concern.

A different, but similarly perplexed, fuel station attendant greeted us in Luton, where the Insignia took just over 64 litres of fuel on board, equating to around 4.1l/100km. I paid up, we checked again and with a gurgle the tank belched out one last gasp of air. Another 1.7 litres disappeared down the filler neck, bringing it back to an unshakable brim.

It had breezed it. With two adults, 30kg of photography gear, a headwind and Brussels traffic against us, the Insignia had not only got us back to Luton with range to spare, but it had made it look easy. We’d averaged 4.16l/100km over 1,587km, enough to cover an incredible 1,683km on one tank of diesel, and all without relying on a breakdown truck.

Building the Insignia

Opel has built cars in Russelsheim since 1899, and the plant now has 3,300 employees on two lines building 800 cars per day, of which 300 are Insignias and the remainder are Astras. The plant handles 70,000 parts per hour, of which 70% are sourced from Europe, and each Insignia takes 20 hours to build.

Insignia significance 

Ian Hucker, European director fleet and commercial vehicles at Opel, explains the importance of the Insignia in a diversifying market, and how the refresh brings it up to date. 

Insignia was designed to be our flagship. It showed everybody what we could do in design, comfort, technology and it’s built here in Russelsheim, so not only is it our flagship car but it’s built at our European headquarters. We had short supply from year one, and with the new car it’s gone flat out once again.

The package works and we’ve tailored it around fleet customers and user-choosers. For example, Tech Line in the UK is very well established and we’ve executed that same idea across Europe. In Germany, that car was running at 50% of orders from a standing start. It’s what the fleet managers typically drive, so when they make decisions on other vehicles in the fleet, it does help us elsewhere.

Fleet is quite traditional; the C and D segments continue to dominate, but the D segment has shrunk in size. The key thing for us is we also need to be in those other segments where the drivers are moving to. Zafira Tourer has grown significantly in fleet this year and one of the reasons is you can move from Insignia without losing the features you’re used to. Then it’s more of a lifestyle choice.

The other thing we’ve seen is four wheel drive variants are up 40%, and for me this is one of the spin-offs of Country Tourer. Yes that’s 5%, and we knew it would be a niche part of the segment, but the awareness building of four-wheel drive capability has really helped. It’s Germany, Austria and Switzerland that are the areas where four-wheel drive penetration has really accelerated.

That diversification of product over the last ten years, where it used to be if you had a Corsa, Astra and Vectra you were pretty much done, the rest was all niche. These days it’s not that clear-cut. So finding these nuances, different ways of approaching the market, such as Country Tourer, are very important to have all bases covered.