After nine months of waiting we have finally road tested a new Euro 4 truck using our own heavy truck test route.

Bearing in mind that most of the truck manufacturers in the UK have been taking orders for Euro 4 and 5 trucks since June, why has it taken this long to allow the press to put one through a full blown road test? To be fair, the lack of demand in the UK has meant Euro 4 right-hand drive production has been scheduled to meet the October 1 deadline, so what trucks the manufacturers have had have been out on customer evaluation. Now that normal service has been resumed, we can continue.

It should not have escaped anyone's attention that a heated debate has been raging for nearly a year over the relative merits of SCR and EGR emissions control systems; two manufacturers' representatives almost fell out during a public debate on the subject!

The SCR camp has been saying that a Euro 4 EGR engine will typically be around 2 to 3% less fuel efficient than a Euro 3 equivalent, and an engine employing SCR will be around 5% better on fuel. The EGR supporters have said their fuel consumptions at Euro 4 will remain unchanged and, of course, there is no need to buy and use AdBlue in their products – unlike engines fitted with SCR technology. The proof of the pudding, as they say, is in the eating – so read on.

Specification

Our first Euro 4 test truck is an 'EGR' MAN TGA 26.440. The TGA is still powered by MAN's extremely capable 10.52-litre D20 commonrail turbo-diesel. At Euro 3, and some early Euro 4 models, it was offered at 350, 390 and 430hp. For Euro 4, the engine is now available at 360, 400 and 440hp, MAN having made some subtle but crucial changes to its design. The 440hp example tested here develops maximum power between 1400 and 1900rpm, with maximum torque of 2100Nm being produced from 1000 to 1400rpm. Exhaust gas recirculation has always been a feature of the engine's design and was used to achieve Euro 3 emissions standards. At Euro 4 the percentage of exhaust gas pushed back through the cylinders has increased to reduce NOx levels and bringing particulate emissions down is an exhaust-mounted MAN PM-Kat particulate matter catalyst. The catalyst is designed to last the whole life of the truck and is claimed to be maintenance-free.

The TGA comes with MAN's Tipmatic version of the ZF 12-speed automated transmission as standard. It has a ratio spread of 15.86 to one and drive is reduced further on this truck through a tall 2.84 to one HY-1350 single reduction axle. Its eight-tonne front axle is suspended on steel parabolic springs and relies on hydraulic dampers and stabilisers to further improve ride and handling. The second mid-lift axle uses twin air bags and the drive axle has four ECAS-controlled air bags and hydraulic dampers.

Braking is courtesy of electronically-controlled discs with ABS and traction control; secondary braking is provided by MAN's standard exhaust valve brake (EVB). A water-operated Pritarder can be fitted as an optional extra. To save weight this test truck was fitted with a fixed fifth wheel and Alcoa alloy wheels. The unit was topped with MAN's LX longhaul sleeper cab and weighed in at 7,740kg, which included 480 litres of fuel but no driver. The unit was running on Michelin X2A Energy tyres and the test was conducted using ROADWAY's similarly shod 6750kg Schmitz Cargobull test trailer. With a payload of 29,410kg the combination weighed dead on 44 tonnes with driver.

Performance

To ensure continuity across our road tests, we set the cruise control on motorways to 52mph. This helps avoid getting mixed up in overtaking duels and also helps fuel economy, a practice being adopted by more and more operators. Selecting drive, the TGA's auto box defaults to third gear on the level ground to pull away. The 440hp D20 develops the same torque output as its Euro 3 430hp equivalent. In order to achieve maximum fuel economy a gentle right foot is required. The engine control unit makes use of all available power on moving off but, with maximum torque coming into play at 1000rpm, it is advisable to feather the throttle to ensure the transmission shifts up at around 1600rpm. The box will normally follow a 3,5,7,9,11,12 pattern.

Once we were making decent headway in seventh gear, we switched the transmission to manual control and used the steering column-mounted stalk to swap cogs. Despite a tall rear axle ratio and us deliberately keeping the engine revs within the 1000 – 1400 peak torque band, progress was deceptively quick. Joining the motorway our 52mph cruising speed was soon reached and we sat back to see how the truck performed. We have been fans of the D20 for some time, having tested two D20-powered trucks around this route in 2005.

The engine drives like it has at least 12 litres to call upon and it will lug down without complaint. On long hills the revs drop, but as the engine reaches 1100rpm it digs in and top can be held in most situations. On 40mph roads, the truck can still be driven in top and we made use of its speed limiter feature. With our speed limited to around 42mph we made the occasional gearshifts reacting to changing road conditions and gradients. In this mode the engine is only using as much power as is required to maintain road speed. As the driver sees an incline he can floor the throttle, which overrides the electronics, and the engine will over-fuel to boost power and torque delivery. The result is a reduction in fuel-thirsty gear changes but with no detriment to performance.

On our timed hill climbs, the TGA responded well and crested both in 11th gear. On the first sharp M3 climb our speed dropped to 43mph and on the second, longer A3 ascent speed dropped to 37mph. Here the superb torque characteristics of the D20 came into play. Most other trucks we have tested require 10th gear but, once the D20's revs dropped to 1060rpm, they sat there and the truck stayed on recording a very respectable time.

The overall route average speed was 48.58mph. This was quicker than the Euro 3 430hp TGA tested in May 2005 by over 1mph and it was only 0.75mph slower than the 530hp Daf XF95 44-tonner tested in September last year.

At The Pumps

As we explained in our introduction, supporters of SCR have said that at Euro 4 an engine employing EGR to achieve Euro 4 emissions standards will use more fuel than it does at Euro 3. The Euro 3 D20-powered MAN TGA 26.430 6x2 tested in May 2005: overall route average at 44 tonnes – 8.23mpg. Euro 4 D20-powered MAN TGA 26.440 tested here: overall route average – 8.45mpg! How can this be? Not only is this the best result we have recorded at 44 tonnes around this route but it is 0.75mpg better than the Daf XF95 we tested last year at Euro 3. Part of the answer, in our opinion, lies in the basic engine design. The D20 broke all records at Euro 3 and, as we have argued in the past, if an engine is fundamentally very fuel efficient it will continue to be so. Other engines may use less fuel at Euro 4 thanks to SCR, but the gains are all relative and not comparative. But MAN has had something up its sleeve.

The new Euro 4 versions of the D20 use a modulating EGR system, which was not the case with the Euro 3 and early Euro 4 versions of the engine where the EGR was either on or off. Using a metering system and infinitely variable EGR valve, the system now only recirculates as much exhaust gas as is required to maintain the emission levels and this in turn is influenced by loadings and the demands put on the engine. The old system recirculated 13% of exhaust gas to achieve Euro 3 any time the engine was under load. The new system recircualtes up to 18% but the average amount of exhaust gas recirculated is now lower. The result is that engine running temperatures are kept down and, providing they are operated within the peak torque band and not driven to use maximum power (between 1400 and 1900rpm – unless absolutely necessary) they will use less fuel than the Euro 3 version. The proof of this is before you.

MAN has built some Euro 4 versions of the D20 that use the old system and these were about 2% worse on fuel than their Euro 3 cousins, but the manufacturer adds that any trucks ordered for UK October delivery will have the new up-rated engines The other key to improvements in fuel consumption at Euro 4 is selecting a higher than normal differential ratio. By doing this, the truck can rely on the excellent torque characteristics of the D20. Performance is maintained at lower engine speeds and consequently the engine stays cooler and uses less fuel. Even on our 29-mile A3 section which includes the 600ft climb from Portsmouth to Hindhead, the truck returned 7.43mpg. Its best motorway cruising figure was 9.15mpg. And all this is achieved without the additional cost of AdBlue.

Ride And Handling

One of the reasons this truck returned a very respectable average speed around the test route is down to its sublime handling. We noticed that in some bends on our single-carriageway sections, where we would normally have to check our speed, we could throw the TGA in and power out, without any sign of understeer. We have the advantage of a curtainsided trailer with a very low load centre, and would not attempt this with a container or tank, but the exercise demonstrated how stable the TGA's chassis and suspension setup is. Steering is precise and on the tighter sections of our route where inch-perfect positioning is vital in corners to avoid clipping the mirrors of oncoming trucks, we found we could direct the TGA where we wanted with steady controlled steering inputs and the truck responded in exactly the required manner.

The truck's ride is smooth and there is little or no detectable cab movement. The service brakes are strong and effective but, thanks to the exhaust valve brake and correct use of engine revs on descents, we only had to trouble them on the steepest of hills or when coming to rest.

A Driver's Eye View

As far as the transmission is concerned we have to admit that we drove the truck in its manual mode for around 85% of the route. At junctions, in slow traffic and on roundabouts we allowed the automatic transmission to do its stuff, but we were asked by the manufacturer's representative to drive the truck for maximum economy and this meant considerable manual intervention based on our knowledge of the route. The auto shifts are better than some we have experienced with the ZF transmission. In Tipmatic's normal drive mode there is not the control offered by competitors' solutions when it comes to lowspeed manoevring. MAN has included a forward and reverse crawler setting to address this.

In-cab noise is at a level that makes driving the TGA an interactive experience. Normal conversations can be conducted over the engine noise so we are not suggesting the truck is noisy, but one good thing is after a few miles the truck can be driven by ear – something this driver prefers! The interior of the TGA cab has not changed much from the last time we tested it but, in line with the TGL/TGM interior, the instrument panel has become more rounded and the dash-mounted buttons have been replaced with a better design. The major difference is the new integrated steering wheel.

MAN has dispensed with the column-mounted cruise-control stalk and the controls can now be found on the right-hand side of the steering wheel. The engine brake and transmission control are still on the steering column. On the left-hand side of the wheel are controls for the radio, cab phone – if fitted – and diagnostics systems. Storage space is ample and the high-roof cab has masses of headroom. Visibility from the driver's seat is excellent and mirrors do not get in the way. The driver's seat controls are far more robust than in previous models and overall cab interior build quality is good. Productivity and operating costs

From previous road tests we have conducted the most important figure is the truck's overall payload productivity. This is average speed multiplied by fuel consumption and payload carried. Until we tested this truck 10,954 was the benchmark – now 12,058 is the benchmark! Thanks to its excellent fuel returns, decent average speed and low chassis weight this tractor takes the honours by a massive margin. When we test a truck with SCR we will have to take into account the AdBlue consumption. This will be done as a percentage of fuel used and the overall productivity figure will be adjusted to reflect this. As the MAN TGA does not require AdBlue its productivity rating stays the same. One down side to EGR is that oil drain intervals are more frequent than with an SCR engine. This is because more soot gets burnt in an engine with SCR and therefore it does not contaminate the lubricant as quickly.

The TGA's oil drain interval is 90,000km on an R&M contract. This is around 10% more than the average for an SCR equivalent. MAN says that 75% of TGA sales are on fixed-price R&M contracts and the company has maintained Euro 3 prices on its maintenance contracts.

Conclusion

One thing Euro 4 has done is to re-write the standards manual. Thanks to the emissions requirements, the design and development engineers have been working overtime to ensure that their chosen solution delivers and is competitive. We will comment how these results compare with SCR tractors as our road test programme unfolds, but we don't mind telling you that this MAN TGA has got the SCR camp on the back foot.

Our test results blow some of the anti-EGR arguments out of the water, and this is down to MAN's engineering expertise. The results could well be beaten by a 44-tonner using SCR, but we don't believe the margin in productivity terms will persuade operators to write EGR off, and most definitely not if they are doubtful about AdBlue. In terms of price, this TGA 26.440 is listed at the same price as the Midlift 26.430 tested by ROADWAY in May 2005.

Test Specification

• Manufacturer: MAN ERF UK Ltd, Swindon
• Model: TGA 26.440 6x2/2 BLS tractor
• Engine type: MAN D2066 Euro 4
• Capacity/cylinders: 10.52-litre six-in-line
• Compression ratio: 19 to one
• Bore x stroke: 120x160mm
• Fuel system: Common rail
• Max power: 440hp @ 1400–1900rpm
• Peak torque: 2100Nm @ 1000–1400rpm
• Emissions control: EGR with PM-Kat
• Gearbox type: MAN Tipmatic 12-speed automated
• Ratio spread: 15.86 to one
• Drive axles: HY-1350 single reduction
• Ratio: 2.84 to one
• AXLE CAPACITY
• Axle one: 8,000kg
• Midlift axle: 7,100kg
• Drive axle: 11,500kg
• Clutch type: 430mm single dry plate
• SUSPENSION
• Axle one: Parabolic springs hydraulic damper
• Axle two: Two bag air
• Rear bogie: ECAS-controlled four-bag air hydraulic dampers
• Brakes: EBS ABS, traction control, discs all round
• Auxiliary braking: Exhaust valve brake
• Tyres: 285/80R22.5
• Length: 6225mm
• Wheelbase: 2600mm
• Width: 2500mm
• Cab height: 3384mm
• Chassis dimensions: 270x85x8mm
• Basic chassis cab weight: 7,740kg
• Chassis list price: £71,973
• EXTRAS
• Door sunblinds: £240
• Air-suspended passenger seat: £475
• Door extensions: £390
• Alcoa alloy wheels: £3,133
• Chassis price as tested: £76,211