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MAN's TGM 18-tonner stands apart from its rivals,

MAN's TGM 18-tonner stands apart from its rivals, thanks to its 12-speed automated gearbox. But when 12 goes in to 18 do you get the answer you want?

Since its introduction towards the end of 2005, MAN's 18-tonner has yo-yoed up and down the UK truck sales charts, seemingly unable to find any consistency In 2010, for example, the TOM was ranked a lowly sixth in the two-axle, 15-tonne GVW plus sector, with a paltry 5.9% market share. In 2011, it rose to third place, with an 11.3% market share. Which of these is a true indication of where the TOM really deserves to be?

TOM shares its cab with MAN's 7.5to 12-tonne TGL range, so its external width is a fairly compact 2,240mm across the doors. There are four cab types: C day; L sleeper; LX long-haul sleeper; and DK crew cab. The test vehicle is the L sleeper, which provides 660mm more internal length than the day cab to accommodate a single bunk. But there is only a modest increase (76mm) in internal height, so any operator planning regular nights out for a TOM really ought to be looking at the LX sleeper, which offers 280mm more headroom than the L cab, but with a weight penalty of 65kg, all carried on the front axle. Its standard front axle is 7,100kg but to better cope with diminishing loads, MAN offers a 7,500kg axle with bigger tyres, as fitted to this vehicle.

MAN offers the 18-tonne TOM in eight wheelbase lengths. At 6,975mm, the test vehicle is not only the longest of these but one of the biggest available on any 18-tonner. Even with the sleeper cab it has no problem accommodating the lengthy (8.5m) curtainsider body.

A refreshed TOM was unveiled at the Hannover show in September, coinciding with the unveiling of Euro-6 engines that will become mandatory at the end of this year. The engines and their ratings are essentially unchanged, apart from the addition of SCR systems as part of the comprehensive exhaust after-treatment needed to satisfy Euro-6. The new TGM's external styling changes are relatively minor. They chiefly involve the use of more black panels — below the windscreen and in the central part of the bumper — which make the screen appear deeper and reinforces the TGS/ TGX family resemblance. But that is still a year away. In the meantime, how does the Euro-5 model fare on CMs middleweight test route?

Technical profile When the TOM was launched in late 2005, its 6.9-litre, six-cylinder D0836 engine was a Euro-4 unit, available with nominal ratings of 240hp, 280hp and 330hp. For the introduction of Euro-5 in October 2009, MAN uprated this EGR engine to give nominal ratings of 250hp, 290hp and 340hp. The test vehicle is a 250hp variant, by far the most popular at 18 tonnes.

According to our analysis of all 18-tonners registered in the UK in 2011, the average 18-tormer has a 7-litre engine, a power output of 238hp and 930Nm of torque. With 6.9 litres, 247hp and 1,000Nm, the test TOM is right on the money The increase in its power (and torque) between Euro-4 and -5 is down to two key changes First, there was the introduction of the next generation of Bosch common-rail fuel-injection, raising peak injection pressure from 1,600bar to 1,800bar. Second, MAN adopted BorgWarner's regulated two-stage turbocharger. This is actually two turbos connected in series into a single unit. By means of a wastegate and by-pass valve they can work either independently or in tandem, with the latter multiplying their boost pressures. This high boost capability allows MAN to recirculate up to 30% of the exhaust gas (to hit the Euro-5 NOx limit) but still pack in sufficient fresh ambient air.

All that clever turbo technology produces worthwhile results: this engine has good power and torque in the critical middle portion of the engine-speed range. Its rated speed is 2,300rpm, but the upper reaches of the power curve are unusually flat. All 247hp is available from just 1,800rpm. Maximum torque of 1,000Nm is above the class average and is spread over a reasonably wide plateau extending from 1,200rpm to 1,750rpm.

The TGM's real distinction is its 12-speed Tipmatic (née ZF AS Tronic mid) automated gearbox, standard on UK specification models. The option is a ZF nine-speed synchromesh range-change 'box, which comes as standard on TGMs in Germany. Weight is not a deciding factor because there is only 10kg between the two boxes Automated shifting is obviously a boon for distribution drivers, so making it standard in the TOM ticks a big box for MAN. Twelve ratios may seem like overkill on an 18-tormer but in the same way that you don't have to use all the keys on a piano keyboard, one can argue that 12 is not too many, but merely enhances the opportunity to be in the right gear at any given moment. But the success of this theory depends on the control strategy; frequent shifting is not only inefficient but becomes wearisome, even if you are not depressing the clutch and stirring the stick.

The other plus point for this gearbox is that it was designed from scratch for automation. Shifts are smoother and faster than those made by ZF's AS Tronic lite, the six-speed automated gearbox offered by Iveco, Daf and Volvo for example on their 18-tormers. That is a manual 'box with external clutch release and shift cylinders and its results are by no means as good.

MAN uses the overdrive version of the Tipmatic 'box in the TOM, so 11th is direct and top is 0.81:1. Married to the 4.11:1 final-drive ratio, this gearing means that when travelling at our motorway cruising speed of 53mph (85km/h) in top gear, the engine speed is 1,480rpm, right in the middle of the peak torque plateau. The engine is still comfortable (at 1,400rpm) in top gear at the 50mph dual carriageway limit, with plenty of flexibility to handle changes in speed or modest inclines without a down-shift. It is only at the 40mph single carriageway limit that top gear becomes marginal, with engine speed down to 1,120rpm, torque shaded back to 960Nm and power down to 150hp. Dropping to 11th gives the benefit of a more fuel-efficient direct drive and engine speed is back up to a more responsive 1,385rpm. The usual gear for running at the 30mph limit is 10th, with CAB COMFORT The TGM tested here is fitted with the L sleeper distribution cab. Even if you do not plan nights out, it is the safe option, yielding residual values of up to 21,500 above the C day cab after three years, according to the used price experts at CAP.

The L sleeper cab is 170kg heavier than the C day cab. It has air-sprung cab mountings rather than the mechanical suspension of the day cab, as well as a night heater.

The driver's seat is also plusher, with lumbar support and heating.

The engine cover rises 260mm from the cab floor, presenting a sizeable barrier hard up against the driver's left leg. This is mitigated to some degree by the absence of a clutch pedal, giving a little more room in the foot well to stretch and shift position.

The cab's roof is a further 1,385mm (4ft 7in) above the engine cover. That's sufficient to clamber from the driver's seat to the bunk, but little else. The taller LX cab takes this measurement up to 1,665mm (5ft 6in), so moving across the cab becomes easier, making nights-out work more acceptable.

Most of the cab's storage space is provided by two lockers under the bunk, supplemented by two trays above the windscreen.

Around the centre dash and doors are several small cubby holes and trays for paperwork, folders, pens and phones.

The layout and feel of the cab errs on the side of functional rather than plush. The rather sombre dark colour of the trim is practical, disguising dirt or marks.

engine speed at a comfortable 1,310rpm. So, on paper this looks like a strong driveline. What's not to like about an engine with a healthy specific output complemented by a slick, automated gearbox with plenty of ratios?

On the road You don't need a tape measure to gauge the true extent of this truck's 7m-long wheelbase: just try backing into a parking space. It wasn't that we struggled; the problem was in recognising that a lot of lateral space is required to do the simplest tasks, whether reversing onto a loading bay, parallel parking outside a shop or just turning around.

Even moving forward requires more forethought than usual and we had to consider well in advance any street furniture, parked vehicles and oncoming traffic. Tight left-hand corners called for a conscious effort to command more road space to avoid putting the back wheel over kerbs or into a ditch and on roundabouts it felt more like redirecting a barge.

At least MAN uses an unusually large steering-wheel, providing a true steering experience without any sense of over-steer. And MAN's interpretation of the compulsory three-mirror set-up needed on the nearside works well, and is particularly appreciated on roundabouts.

Although effecting manoeuvrability, the lengthy wheelbase certainly creates a smoother handling experience, with the truck sweeping gracefully around bends The engine reinforces that feeling of smooth progress At 53mph (85km/h) in top gear on the motorway, the first section we tackle on this route, the engine is delivering all 1,000Nm of its peak torque and 208hp of its 247hp, providing comfortable performance with some oomph in reserve to tackle gradients. There isn't much that can slow the TOM and we noticed how trucks that were not so well endowed struggled with the undulating terrain of the westbound M4.

At 40mph (64km/h) top gear is only an option on the flat or downhill; to achieve it you have to force the automated 'box to make the change by switching to manual. When running on A-roads,Tipmatic flitted between 10th and 11th to cope with differing gradients, keeping the engine speed around 1,300rpm, still on the peak torque plateau. We could hear the turbocharger kick in and drone, one stage for shallower climbs or the much louder sound of both stages working together for steeper ascents.

Before starting the test we had wondered if 12 ratios and automated shifting would prove to be too much of a good thing, with the gearbox making too many shifts as it worked to keep the engine in its optimum speed range. It is true that there were more shifts than in the average manual 18-tonner, but because each shift is smooth, it never became annoying. The 'box will make either single or block changes up to ninth gear — the weight of your right foot can influence that — and then it is almost exclusively single gear steps from ninth to top.

Like any automated shifting system, the programme's default is always to maintain progress, so when on the cusp between hanging onto a gear or a down-shift, Tipmatic chooses the latter. On some uphill gradients where we could see the road was about to level out, we switched to manual to prevent an unneeded down-shift. Occasionally, we used a driver's eyes and judgement to select one ratio higher than Tipmatic thought best, but only because we could interpret the road conditions better than an unseeing gear-shift programme. But this was only in an attempt to optimise fuel consumption: left to its own devices we have no doubt that Tipmatic would have made a decent fist of the job. It certainly avoids the sawtooth progress and unhealthy engine speeds when six ratios are all you have to take 18 tonnes up hill and down dale. Given the choice, we would take a 12-speed every time. Mind you, it is a more difficult decision if the choice is between MAN's 12-speed Tipmatic and the Mercedes-Benz 8-speed PowerShift automated gearbox in the new Antos 18-tormer.

Although an 18-tonner does not roll as well as a heavier artic, it is still good to have a secondary braking system to supplement and conserve the service brakes. The TOM has MAN's exhaust valve brake (EVB), which is claimed to generate up to 60% more retardation than the usual simple butterfly valve in the exhaust. As well as closing an exhaust butterfly valve, EVB also opens one exhaust valve per cylinder during compression and power strokes, increasing the amount of exhaust back-pressure. EVB shaved speed most effectively when approaching roundabouts and during the numerous descents on this route. We can testify that it is certainly more useful than a common-or-garden exhaust brake.

Productivity CM has taken a rather meagre total of just four 18-tonners around our Welsh test route in recent years, three of which have been Euro-4. So the TOM is the only Euro-5 contender, making close comparisons difficult. To compound this situation, this particular truck — sourced from Dawsonrentals — is clearly not what most manufacturers would put in their demonstrator fleet. Not only is it burdened with a high, long body but with less than 2,500km on the clock, the drivetrain must still be rather tight. So this test amounted to quite a gamble for MAN Truck & Bus UK.

But it paid off. Despite those disadvantages and running in wet and windy conditions, the TOM bettered the three Euro-4 models in terms of fuel economy (see Top Four sidebar). That statement needs some qualification, however, because none of the other three is among the leading contenders in the UK's 18-tonne sector. Nevertheless, that is not to take anything away from the TOM: an overall figure of 13.08mpg is a decent result for an 18-tormer, especially one with a tight driveline and such a big body A Daf CF65.300 (also a Euro-5 spec) managed an immensely impressive 14.25mpg but that sported a comprehensive air-kit and was measured over the Scottish route with a predominance of motorway running.

What is most remarkable is the TGM's sheer consistency, turning in a tad under 13.1mpg on both the motorway and the A-road/urban sections Perhaps that is where the multi-ratio auto gearbox comes in, providing the right gear for every occasion.

The Volvo FL 240 — with a six-speed manual box — matched the TOM on the motorway but fell short on the A-road, dual carriageway and urban section, recording just 11.7mpg (CM, 6 December 2007). The icing on TGM's cake is that it needs no AdBlue. Even at Euro-4, which called for less AdBlue than Euro-5, the Volvo consumed AdBlue at the rate of 3.6% of its fuel consumption. The TOM averaged 672km/h around our 367km test route, 3.2km/h faster than the Volvo. Honours were even between the pair over the two timed hill-climbs on the route, despite the TGM's extra 80Nm of torque and additional 10hp.

With full fuel tanks (300 litres) and no driver, the TGM's chassis-cab weight is 5,712kg, slightly heavier than Volvo's 5,570kg, but the comparison is not fair: the Volvo carried 100 litres less fuel, had a day cab instead of a sleeper and its wheelbase was 1.6m shorter. With these differences taken into account, the MAN is lighter. • Under the bonnet The 6.9-litre, six-cylinder D0836 engine produces 247hp peak power and 1,000Nm maximum torque. MAN uses Bosch common-rail fuel-injection and BorgWarner's regulated two-stage turbocharger, which is two turbos connected in series into a single unit. By clever manipulation of a waste-gate and by-pass valve they can work either independently or in tandem, with the latter multiplying their boost pressures. This enables the engine to deliver excellent power and torque in the critical middle portion of the engine-speed range. Maximum torque of 1,000Nm is above the class average and is spread over a reasonably wide plateau extending from 1,200rpm to 1,750rpm. The engine's rated speed is 2,30Orpm but all 247hp is available from just 1,800rpm, so it is rare for the automated gearbox to allow engine speed to get close to the maximum.

- - Torque 1,000 200 00 1,600 1,800 2,000 2,200 2,400 Engine Speed (rp[] 260 240 220 200 7E2 1 160 40 120 100 1 800 600 00 1 200 1 000 800 600 400 200 THE COMPETITION Oaf LF55/CF65 Daf takes a two-pronged attack to the 18-tonne market with the number one seller LF55, for local distribution work, supported by the CF65 for long-distance work. Safe and familiar, these trucks have a market share that is the envy of other manufacturers. New versions with Euro-6 Paccar-badged Cummins ISB engines are due to be unveiled at the CV Show in April.

Mercedes-Benz Axor Axor has been popular since it succeeded the Atego at 18 tonnes. It can have a 6.4-litre engine at 240hp or 290hp, or a 7.2-litre with 330hp. The all-new Antos is poised to replace the Axor at Euro-6, powered by a 7.7-litre engine available in five ratings from 235hp to 349hp. Its eightspeed PowerShift automated transmission is sure to prove popular with drivers.

Scania P-Series This 18-tonner enjoys a strong following due to its image, solid engineering and 9.3-litre, five-cylinder engine. Its weight and price doesn't seem to deter hauliers. Most choose the 230hp rating, a modest output but with ample torque (1,050Nm from just 1,000rpmi. The Euro-6 version will be available in SCR-only or EGRplus-SCR versions from 250hp to 350hp.

TESTER'S VERDICT On the strength of its performance during our test, the TOM deserves its third place in the sales league table of 18-tonners. Fuel economy and payload are respectable but not startling. The consistency of fuel economy across a variety of roads is noteworthy though. Performance is good, thanks to an engine with above-average power and torque that is willing to lug. Good marks for brakes, steering and ride comfort too.

On balance, we also give a thumbsup to the 12-speed automated gearbox. It's an unusual choice at 18-tonnes GWV and yes, it did throw in rather more shifts than is usual, occasionally hunting between gears as if spoilt for choice. Anyone who has been through an economy driving course and seen the instructor count his gear-shifts will know that fewer generally is regarded as better. But the shifts are so good that this tendency never got to the point where it became irritating, and we cannot argue with the respectable fuel economy nor brisk performance and journey time. And we prefer this designed-from-scratch auto 'box to ZF's AS Tronic lite six-speed manual-with-added-shifters offered by rivals. The cab scores a so-so rating: there are swankier ones, but it would be churlish to complain about the TOM.

The only poor mark — one out of four — in our scoring matrix is that for manoeuvrability. We can judge only what we drive, and there is no getting away from the fact that this particular lengthy TOM is cumbersome. As we said at the outset, there are seven other wheelbase options, all of them shorter. But even choosing one of them is not the entire answer because the TGM's turning circles are not that good. On a like-for-like basis, those of Daf's CF65, for example, are considerably smaller, giving it a worthwhile advantage in tight situations.