• Turbo, or not turbo: that is the question. If
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the noble Bard were alive today (and happened to be holding down a job as a CM headline writer) he could undoubtedly make something out of the thankless struggle to beat emissions standards. Perhaps A Midsummer Night's Green, Julius EECaesar, Anthony and Cityfiler, or even Much Ado About Particulates.
As one of the world's largest producers of diesel engines, Mercedes would be a likely choice for the Shakespearian lead role: it knows as well as anyone the diffi cult, and expensive, decisions required to keep pace with the targets set by pressurised politicians.
Judging whether to follow the turbo route invariably plays a central part in the process, and two examples from the current Mercedes-Benz line-up illustrate the range of technical solutions demanded by current and threatened legislation.
At the top end of the range the writing is on the wall for those popular fleet tractors the 1726 and 1729 with their naturally aspirated 15-litre 'ee-eights. With turbochargers seemingly essential for clean
burning heavy diesels, expect the big unblown vee-eights to be pensioned off soon , in favour of lighter turbos, probably derived from the 1733's 11-litre vee-six.
For the lighter panel vans, such as this week's test vehicle, the 4.6-tonne GVW 410D, Mercedes has adopted a somewhat different approach. Many competitors have chosen direct-injection designs, often augmented by turbochargers, for their Light commercials; Mercedes has instead come up with a new family of naturally aspirated indirect-injection diesels.
The most powerful member of this family, a 2.9-litre 70kw (95hp) fivecylinder unit, became available in the UK this summer.
While the 3.5-tonne 3101) was introduced as a gutsier alternative to the 308D, the heavier 410D actually replaced the 408D altogether, putting the 4.6tonner on more equal terms with competitors which were all more powerful.
That competition effectively amounts to only three vehicles, other manufacturers prefering to contest the major markets at 3.5 and 7.5 tonnes where most sales lie. Thus, the 4101) is up against the recently revised Iveco Ford TurboDaily, Volkswagen's faithful LT, and the 50 Series from Renault.
Renault's challenge deserves mention here, partly because all versions of the 50 Series powered by the naturally aspirated Phaser 90 have been dropped (ironically for those same emissions-led reasons already mentioned), but mainly because the new B range is about to be launched in the UK. This new arrival, which is very close to the TurboDaily in specification, is designed to give ailing Renault new strength in the retail sector.
Traditional rivals like the 410D will not give up without a fight, of course, and complete with its fresh driveline, it sells for a reasonable E17,585. Mind you, a glance at our In Brief box, shows that buyers would be wise to include options in any cost comparisions.
• BODYWORK
The 4101) is available as an integral van or a chassis-cab, in both cases with a
3,700mm wheelbase. The van version has a high roof and full-height rear doors as standard; at 11.4m3 it is the most capacious of the Mercedes Ti range.
Because of its large capacity, the 410D, like its petrol equivalent the 410, is actually available at a choice of two gross weights.
With the 308D only available with the shorter, 3,350mm wheelbase, a 410D downrated to 3.5 tonnes gives operators the additional cube without the additional hassle of tachographs and 0-licences; Mercedes says that half the buyers of the 410D and its predecessors specify the downrated version.
Our vehicle is plated at 4.6 tonnes, however, and ready for the road it offers a competitive payload in the region of 2,400kg.
The load area itself is reasonably practical, having a regular shape with nearvertical side panels, and plenty of scope for securing goods or mounting racks using the bracing struts. Access via the rear and side doors is good and loading with a lift truck shouldn't cause any difficulties, although the twin rear wheel layout does make the space between the wheelarches a bit tight at 1,030mm.
Putting heavy objects in by hand is a less appealing prospect thanks to a deck height of over 600mm, and while sliding items in is one solution, a rear step would certainly help the task of climbing aboard. Once inside, there is enough headroom for all but the tallest to stand erect. At 3,900mm, the load bed is also long enought to cope with unwieldly goods such as carpet rolls.
The optional full-height bulkhead provides welcome security for the driver and passengers, as well as bracing the body and cutting down noise levels. Obviously, however, it restricts access to the load from the cab (one of the advantages of going for an integral van rather than a chassis cab with independent bodywork), and prevents the addition of a Luton-type tray.
• DRIVELI NE
The five-cylinder 2,874cc diesel is effectively the 2,299cc four from the 408D with another cylinder added on, so it comes as little surprise that its ouputs are ahead of its predecessor.
Power is up by 20% to 70kW (95hp) at 3,800rpm, and more importantly torque is 22% higher, peaking (or plateauing, given Mercedes' current fetish for flat torque curves) at 192Nm (142lbft) between 2,400 and 2.600rpm.
To take full advantage of the increased urge, Mercedes has raised the overall gearing, now specifying the 4.11:1 rear axle as standard in place of the 4.38. This not only stands to benefit both fuel consumption and noise levels, but also makes a road speed of 113km/h (70mph) a more practical proposition.
• PERFORMANCE
Like the 310D we tested earlier this year (CM 5-11 July), the new engine has transformed the performance of a product not renowned for its speed. Even with a full payload the 410D covers the ground at a satisfying rate.
The five's most impressive feature is its flexibility. The wide torque spread allows the revs to drop below 2,000rpm without recourse to a hasty gearchange (unlike the more peaky TurboDaily, for example).
The 410D is happiest at single carriage way A-road speeds, however, for although it is capable of maintaining the legal limit on the motorway, noise levels are a bit wearing after a time. The company has made good progress in making its vans quieter in recent years (witness the 410D's 80.5dB(A) at 113km/b, compared with 87.0dB(A) from the 407D tested in 1988), but there is still room for improvement: the latest TurboDaily is quieter at speed, and its engine is somewhat smoother.
The gearing represents a reasonable compromise, with no awkward gaps between the ratios, and the shift is also pretty good, although the movement from the dog-leg first into second is difficult to make quickly (resulting in the temptation to miss out first, to the detriment of the clutch's lifespan).
• ECONOMY
Mercedes seems to have got the performance/economy balance about right with the 410D. Fully laden, it returned 13.51it/100km (20.9mpg) overall while lapping our Welsh test route at a fast average of 74.5kmih (46.3mph).
The fuel consumption also proved very consistent over both sections of the journey, at 13.81it/100km (20.5mpg) on the motorway and 13.41it/100km (21.1mpg) over the A-roads.
Despite all this, the newcomer doesn't quite inherit the efficiency crown, which remains with the direct-injection turbodiesel in the TurboDaily; with a bigger body • and a 5.0-tonne gross weight, the latest 49.10 Turbo Daily achieved 13.01it/ 100km (21.8mpg) overall, albeit at a slightly slower average speed.
• HANDLING
With the firm leaf springs at both ends, the road behaviour of the 410D was never going to be that sophisticated, and the ride is indeed a bit on the bumpy side. But overall the Mercedes is safe and predictable, even when provoked.
The optional power steering must be recommended, especially for those contemplating urban delivery work, as the non-assisted system gets a bit heavy at manoeuvring speeds. Combined with a decent lock, our vehicle could be threaded through crowded city streets with ease.
Stability is reasonable at speed, despite a slight tendency to get buffetted round by strong gusts of wind. The service brakes are up to the job of slowing the van in a hurry. The handbrake held rock solid on our test slopes.
The 4100 shares its cab with other members of the Ti range; like them it has its strengths and weaknesses.
Access is good, thanks to a wide door and a convenient step, and cross-cab movement is acceptable for multi-drop delivery work.
A height-adjustable perch helps the process of sitting comfortably, and like the rest of the vehicle, the interior is well made from good quality materials which should endure use and abuse.
Beyond that, the cab has difficulty disguising its age, and the general presentation of instruments and controls, the driving position, and the heating and ventilation system is not to the same standard as the more modern products in the Mercedes range.
• SUMMARY
With the new 4100, Mercedes has given its largest Ti van the power it deserves, and in so doing has helped keep an ageing product up with the competition.
The latest five-cylinder diesel provides an attractive blend of perfomance and eco nomy, and those familiar with the marque should find the 4100 an admirable successor to the 407D and 408D, either at 3.5 or 4.6 tonnes GVW.
It is a bit noisy on the motorway, however, and the TurboDaily may well be a better bet if a lot of continuous highspeed work is contemplated; and the interior is well overdue for an update.
Nevertheless, the solidity of the Mercedes augers well for a long service life, and even if the reality of the product doesn't always live up to it, the company's image is a bonus fopfnany buyers.
E by Peter Watt