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OPERATOR

13th April 1989, Page 57
13th April 1989
Page 57
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Page 57, 13th April 1989 — OPERATOR
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The latest Mercedes-Benz high-roof 308D maintains its family tradition of tou•h, well made dependability, which is now combined with a quieter, more frugal engine.

• If the Brussels Motor Show in January was as plagued with hyperactive youngsters as our Birmingham show, then swarms of them would have been heading for the Mercedes-Benz stand. The Ti range was due for a major update after 11 years in production, and the new models were about to be unveiled.

I wonder how the mob reacted, however, when they found the stand and saw that the new vans looked just like the old vans, except for the large black plastic strips around the windscreen. They most likely tried a quick "Got any stickers?", removed any collectable items not securely attached to the vans and saved their flash bulbs for the more glamorous vehicles in other displays.

None of this will have worried the Mercedes-Benz management, of course. It learnt long ago that gradual but thorough development breeds long-term success — jumping on the latest bandwagon is not for them. The revised T1 models may not appear dramatically different, but changes beneath the skin have readied the vehicle for a further five years in production, and the modifications exemplify the 'evolution not revolution' philosophy.

The most important part of the update is the use of a new 2.3-litre diesel engine, developed specifically for commercial applications. It is claimed to be more fuel efficient than its predecessor and also permits longer service intervals. These factors, along with revised gearing and improved aerodynamics, have allowed Mercedes to boast of a significant improvement in running costs.

To put these claims to the test, we have been looking at what promises to be one of the most popular models in the range: the high-roof version of the 308D panel van which supersedes the 307D. At 212,630 (ex-VAT) for the standard-roof van, the Mercedes appears reasonably competitively priced; add on the cost of the extras fitted to our test vehicle, however, and the price rockets to a less acceptable .E15,744.

• BODYWORK

The 308D's popularity with parcel companies makes the high-roof a commonly requested option. For the past couple of years, full-height rear doors have been standard in the £937 package, so access to the load area is excellent.

At 9.6m3, the high-roofs load volume is pretty good, but for those looking for space above all else, vans such as the Renault Master (at 12.8m3) are obviously better bets. The load area itself is practically shaped, however,and there are plenty of lashing points built into the mid rails.

Being a rear-wheel-drive design, the 308D does not have a particularly low loading lip, but at 555mm (laden) it is as good as most of its competitors. The front-wheel-drive Renault Master leads the way here, with its excellent laden figure of 360mm.

The 308D's payload allowance is modest at 1,450kg though it is unlikely that many parcel companies will require much more. No bulkhead is fitted as standard, but for driver safety, and to control the noise levels, we would recommend one of the optional full-height load partitions.

Mercedes has made much of the aerodynamic improvements to the pugnosed Ti range. A 17% reduction in drag is claimed for the models fitted with the plastic mouldings above and to the sides of the windscreen: the reduction will be less on the high-roof variant tested, which does not have the strip above the screen.

• DRIVEUNE

The new 2,299crn3 IDI diesel is not related to the outgoing 2.4-litre engine, being derived from the 2.0-litre unit used in the company's passenger cars. A great deal of stress has been put on reducing emissions, and the new diesel beats all projected EC legislation by a 30% margin, including the rules on particulates and nitrous oxides limits.

Mercedes claims the engine is both

more economical and more powerful than its predecessor. Output is up to 58kW (79hp) at 3,800rpm, with 157Nm (115lbft) of torque provided between 2,000 and 2,800rpm, reflecting the company's policy of designing low-revving engines with a wide torque spread.

To match the changed characteristics of the diesel, a new overdrive gearbox has been chosen, with a direct fourth gear and a 0.806:1 ratio in top. The standard final drive ratio is now 4.857:1.

• PERFORMANCE

At the 3081)'s (NW of 3.5 tonnes, performance is best described as pedestrian (walking is sometimes faster). In-town acceleration is particularly poor, so 'express' parcels operators should beware, just in case they are prosecuted under the Trade Descriptions Act!

Wide spacing between the intermediate gears does not help matters, although the torquey engine tries its hardest to keep the vehicle moving. Fortunately the new diesel is considerably refined, and even when being asked to work hard it does not become unpleasantly raucous.

On the motorway, noise levels remain low in the overdrive top, and the 308D can cruise comfortably at the legal limit — until it meets an incline, when it steadily loses speed. The Mercedes also struggles on steeper slopes, and failed to climb the 25% (1-in-4) hill at the test track.

Operators who run heavily laden most of the time should note that the 310D, with a 70kW (94hp) 2.9-litre five-cylinder diesel is scheduled to arrive in about a year. With this engine performance should be more comparable with the turbocharged diesels which are now fitted by most of the competition.

The revised gearbox retains the arrangement of having first gear on a dogleg, and has a slow change not helped by a poorly defined gate (the new Transit box is significantly better). The clutch has a good progressive action, but is rather heavily sprung.

• ECONOMY

Mercedes suggests that fuel consumption is up to 20% better in the new models, and this is born out by our results. At 12.21lit/1001un (23.2mpg) the laden 308D used 17.8% less fuel on our test route than the high-roof 307D tested previously (CM 1 June 1985), albeit at a slightly lower average speed.

In absolute terms such a return is not. bad, but you need only look at the Fiat. Ducat° Maxi turbo-diesel to put the figures into context.

The Fiat not only has better fuel consumption (11.11n/100km/25.4mpg), but also offers far better overall performance than the Mercedes.

Overall running costs should remain low on the diesel-powered Mercedes 308D van, however, since new features like hydraulic tappets permit extended service intervals (oil change, 10,0001un; major service, 30,0001un).

• HANDLING

The handling of our test vehicle was greatly affected by the use of power steering (a 2647 option).

Combined with the van's good lock, this makes tight-corner manoeuvring a doddle, and considerably eases the driver's burden round town.

At higher speeds, however, the ride becomes slightly nervous, while at the same time the steering lacks precision. As a result small corrections — to compensate for a gust of wind on the motorway, for instance — tend to be difficult to judge accurately.

Road behaviour is otherwise good, with little body roll around corners, and the suspension soaks up most larger irregularities with little difficulty, especially when laden. Braking is also competent, with a nicely progressive feel to the pedal and plenty of stopping power.

• INTERIOR

The interior is one area of the 308D which is beginning to show its age. The latest update has revised certain aspects, such as the trim materials, and the cab will undoubtedly wear well, but there remains room for improvement.

The dash is very basic, with a large, poorly calibrated speedometer but no tachometer.

The speedo is flanked by warning lights, but in bright sunlight these are very difficult to read. The siting of the minor controls is also rather unsatisfac tory: they are spread about on various vacant areas of the fascia.

Finding a comfortable driving position is aided by having a seat with plenty of adjustment, but the pedal positioning has been changed for the worse in the switch from left to right-hand drive. The throttle is perched at an angle over the wheel-arch and the brake pedal is rather high, while the driver's left leg fights a losing battle with the engine cover.

The provision for fresh-air ventilation is also very poor with a lack of useful vents. The driver is discouraged from using the booster fan because at its higher speed it emits a howl not unlike a Transylvanian male voice choir.

Opening the windows helps, of course, but this presumably ruins the work of • those black plastic strips.

II SUMMARY

Britain's parcel fleets love the 307D for its ruggedness and dependability, and the changes incorporated in the 308D should reinforce this loyalty.

Improved fuel economy, a more powerful, quieter engine, and a decrease in servicing requirements all point to a better balance sheet. Build quality is tangibly better than most of its competitors, while load volume and payload should meet most needs.

To be set against this is rather poor performance when fully laden: the forthcoming 3101) may be a better bet for operators who need the speed. Mercedes' pricing policy may also be a shock to some who don't realise that many features such as a radio are extra-cost options.

An interior which is beginning to look rather dated and the unsettled high-speed ride are other areas which could have been improved in the updating procedure.

But overall the latest 3081) should be just what regular Mercedes buyers are looking for, and will undoubtedly help Mercedes-Benz consolidate its fifth place in the van market.

CI by Peter Watt

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People: Peter Watt, Maxi
Locations: Birmingham

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