Mercedes-Benz E 300 BlueTec Hybrid 2013 Review - International

Mercedes-Benz E 250 CDI and E 300 BlueTec Hybrid

Mercedes-Benz has cut through the issue by offering two cars in its new E-Class range that have both sides covered. And the icing on the cake is that the hybrid is a diesel as well. We have previously driven the upgraded E, but a direct assessment of the two eco-friendly sedans was warranted, we believe – sort of a mini-comparison.

Here's the E 250 CDI in the one corner, expected to be the volume-selling E-Class variant in Australia, matched up with the E 300 BlueTEC Hybrid – a completely unknown quantity in this market.

PRICE AND EQUIPMENT

The rumour is that full Australian price and specification details will be revealed next month. Benz has confirmed in the meantime, however, that the Adaptive High Beam Assist Plus safety feature will be standard for the E 400 and E 63 models, but for everything else (including E 250 CDI and E 300 BlueTEC Hybrid), it will be available as part of an option pack. In the main though, our rule of thumb is that high-tech safety features are likely to be rolled out as standard across the local range. And a Euro-spec brochure provided by the events staff for the international launch backs up that view, indicating Attention Assist, Collision Prevention Assist, Pre-Safe and Neck-Pro will be standard.

How will the E 250 CDI and the E 300 BlueTEC compare for price? As we've already noted, the premium for the hybrid model might be anywhere up to $17,000 beyond the price of the E 250, going on current pricing for the pre-update E-Class, as well as insinuation from Mercedes-Benz Australia. That sort of money sounds like a lot, but pales in comparison with even the starting price of the E-Class range in Australia – $80,000 – reflecting the nominal prices buyers accept to get behind the wheel of the large Merc.

Whatever premium Benz charges for the hybrid model will be offset by extra features not fitted standard to the E 250, and driveability gains – faster acceleration, better step-off, quieter running. And as we know from the past Benz dealers will haggle, so don't expect transaction prices for the hybrid (or the E 250 for that matter) to be a mirror image of the manufacturer's list pricing.

In parallel with the diesel, the electric motor supplies enough added performance to shave 0.4 seconds off the E 250 CDI's 0-100km/h time of 7.5 seconds. Yet fuel consumption is better too, with the hybrid achieving 4.2L/100km in NEDC combined-cycle testing – versus 5.2 for the E 250. The motor is situated between the engine and the transmission, and operates as an alternator when the driver lifts the foot off the accelerator. By default, the E 300 BlueTEC will launch using electric power alone, unless the driver demands a higher rate of acceleration. Power for the motor is supplied by a lithium-ion battery under the bonnet.

Pictures don't quite do it justice; seeing the car on the road – with the impact of its daytime running lights achieving their full visual effect – is enough to make the casual observer perform a double-take. It is better proportioned, better rounded in more than one sense of the word and altogether less fussy-yet-conservative.

From behind the wheel, the E-Class is a more cohesive design than models from the past. Switchgear was largely as it has been in the E-Class for years, the only difference being the gear shifter on the steering column, which posed no challenge at all, after years of using the same setup in other Benz models. Two stalks on the left side of the column (including one for the cruise control) took a little while to get to know one from the other. The cruise control stalk was the one you want to flick to indicate change of direction, as indeed happened on one occasion.

Among the rest of the trip computer graphics, the hybrid's energy-flow graphics provided an exemplary case for other vehicle designers to follow. The display was simple and intuitive to take in at a glance. White arrows to the rear wheels in the display's elevated cut-away indicated when positive torque was channelled through the final drive system – and from either the engine or the electric motor, or both – and green arrows away from the drive wheels clearly illustrated energy recovery in progress.

The hybrid we drove was the wagon, rather than the sedan we will see in Australia. It did provide an impression of the way the E 300 BlueTEC will shape up however, and was directly comparable in most respects with the E 250 CDI sedan supplied for the drive program.

Both cars delivered plenty of room front and rear, but, for this writer, access to the driver's seat was hampered slightly by the rake of the A pillars – particularly when the seat was initially adjusted further forward. The seats themselves proved comfortable and required little adjustment to suit the needs of most drivers.

Rear cargo space was quite long, although shallow in the case of the wagon, with room under the floor for a full-size spare, but occupied in part by a tyre repair kit on the European drive program.

Where the revised E-Class breaks new ground is its raft of exotic and sophisticated electronic safety features that one will only find on a high-end luxury car – and especially a Benz. Some of these features, such as Active Parking Assist, for instance, blur the lines between safety and convenience.

A multi-purpose stereo camera located between the rear-vision mirror and the windscreen looks forward of the car in two different directions, at an angle of 45 degrees and a range of up to 50 metres. Visual data from the camera is fed into different safety systems, including Traffic Sign Assist (which we won't get in Australia) and Brake Assist Plus with Junction Assist. According to Benz, the camera can identify pedestrians in the road ahead of the car. Junction Assist refers to the vehicle's ability to 'see' pedestrians and traffic crossing in front of the car and avoid a collision accordingly. Through the Collision Prevention Assist system, at speeds up to 50km/h the E-Class will automatically initiate emergency braking for a pedestrian in front of the car, as well as vehicles and other obstacles.

An additional 360-degree camera facility monitors all four sides of the vehicles and provides input for Distronic Plus with Steering Assist, Active Lane Keeping Assist and the Active Parking Assist system, which is also aided, naturally, by ultrasonic sensors located in the bumpers. These detect objects at distances ranging from 1.2 metres to up to 4.5 metres, in the case of the side-looking sensors in the front bumper. As the car turns while reversing, the front end moves through a larger lateral arc, necessitating the longer range ultrasonics. Active Parking Assist can deliver both reverse and angle parking.

The E-Class also raises the ante with on-board radar. A multi-mode system facing the rear detects objects up to 80 metres away in a 16-degree sweep, or through a 30-metre range over an angle of 80 degrees. The former is designed to activate the Pre-Safe Plus system, which prepares the car and its occupants for a rear-end collision in the event it detects a vehicle approaching from behind at a speed and distance it deems unsafe. First it flashes the brake lights to alert the driver of the other car and then it tensions seatbelts and prepares other passive safety systems for deployment. Finally, it clamps down hard on the brakes to reduce the chance of the Mercedes being pushed forward into other vehicles or pedestrians and incurring further damage or injury.

The secondary radar system at the rear covers not only the area immediately behind the car, but also the lanes adjacent, on either side of the car, to feed data concerning vehicle positioning into the Active Lane Keeping Assist system. Other radar systems include short range radars (30-metre range/80-degree scope) to cover the car's rear three-quarter blind spots, a forward-looking short-range radar and a long-range radar (200 metres/18 degrees) with a mid-range scan facility (60 metres, 60 degrees).

All radars support Active Lane Keeping Assist, but the forward-looking units are also tied into Collision Prevention Assist and Distronic Plus with Steering Assist. Collision Prevention Assist reduces the prospect of the Mercedes slamming into the rear of a car or other solid object in front, while Distronic Plus not only keeps a safe braking distance between the Mercedes and the car in front, it also applies some torque to the steering wheel if the driver is asleep at the wheel and the car is moving out of its lane.

In contrast, Active Lane Keeping Assist, uses braking on one side to 'turn' the car back into its lane if there's danger of a side impact occurring. The safety system will only apply the brakes to affect this manoeuvre where the road is divided by an unbroken white line on the road. If the lines are dotted the system will simply transmit a vibrating pulse through the wheel to alert the driver the car is leaving the lane without the indicator operating.

Other safety features fitted include Attention Assist, to keep the driver alert; Active Blind Spot Assist, which alerts the driver to a vehicle positioned in a blind spot; and Active High Beam Assist Plus, which has definitely been cleared by the federal government for ADR approval. Mercedes-Benz has confirmed the advanced lighting system will be fitted as standard to E 400 and E 63 AMG models sold here, but will have to be specified as part of an option pack on the lesser cars.

All E-Class models gain LED tail lights and part-LED headlights, but those vehicles with Active High Beam Assist Plus feature full LED systems. The LEDs offer the flexibility of diminishing light in specific areas and directions to keep high beam operating to cover all areas of the road, without dazzling on-coming drivers. In effect, the system automatically adjusts the throw and power of the light in the direction of the on-coming vehicle, placing that car in a contrived 'shadow', without reducing the coverage anywhere else. The system responds automatically and adjusts the shadow to stay with the on-coming car as it approaches and its relative angle and proximity change.

Conversely, the BMW ActiveHybrid5 is one of the 'performance' hybrids in this market segment (along with Infiniti M35h and Lexus GS 450h), but can't be said to be a rival to the E 300 BlueTec Hybrid. For a start the BMW is more expensive than we expect the Mercedes to be when it arrives in local dealerships from June. Then there's the consideration that the BMW's 3.0-litre six confers an unfair performance advantage – which is diminished in a hybrid by its 6.8L/100km fuel consumption.

There are a fair number of large sedans that could be cross-shopped against the E 250 CDI – among them the Audi A6 2.0 TDI, the Infiniti M30d (at a pinch) and the Jaguar XF 2.2 – but hybrids combining diesel power with electric... that's a market niche Benz practically has to itself. Volvo's V60 Plug-in Hybrid is diesel-powered, but it's a smaller vehicle and a plug-in. Also, there's no word yet on whether we'll even see that car in Australia.

With just 20kW available from the electric motor it quickly ran out of puff as soon as the road headed up hill, compelling the diesel engine to cut in. But credit to Benz, the electric motor provides just enough supplemental grunt to sand off the rough edges of the diesel's character without drawing excessive power from the lithium-ion battery. Based on how the E 300 drove, you'd have to say that the engineers have judged very finely the conflicting needs of power/performance and efficiency in this large car.

With the E 300's diesel usually not required to start until the car was already on the move, the whole process – and the symbiotic nature of the hybrid drivetrain – led to altogether smoother operation than in the case of the E 250 CDI. On just one occasion was the E 300's power delivery less than flawless: on a downhill run as the system shut down the diesel while it was still providing engine braking through the transmission.

Other than that, the system worked with the kind of emollient functionality we've come to expect of a Benz passenger car. It additionally provided the same sort of driving characteristics we've previously experienced in plug-in hybrids, but the E 300 is not a plug-in. Compared with conventional hybrids, such as Toyota's Prius, there was none of the CVT-based droning and the driving experience is simply one of a vehicle that is really quiet most of the time, with just a hint of driveline vibration when the diesel is operating.

With the diesel engine providing the bulk of the motive power, it's bound to be used more frequently than the internal-combustion engine in a plug-in, the likes of Holden's Volt, for instance, or the Volvo V60 Hybrid – which is the only other diesel-powered hybrid this writer has previously encountered. However, while the diesel did fire up sooner than ideal, the E 300 was still averaging 7.1L/100km, as opposed to the 9.4L/100km posted by the E 250.

If the power output of the electric motor seems anaemic, there's a decent level of torque available for launch. The electric motor of the E 300 develops up to 250Nm immediately from the moment the driver plants the foot, so there's no waiting around for the diesel engine's turbo to build up a head of steam. And it's in that context, contrasting with the E 250 CDI, where the 20kW and 250Nm seems more than adequate. Should the driver need more performance from a standing start (turning right across traffic, for example), the diesel engine fires up promptly and joins the chorus.

When it came to driveline refinement specifically, the hybrid was clearly superior to the conventional diesel, which Benz expects to be the volume-seller in the range. The difference between the two was the hybrid drivetrain would absorb some of the roughness normally expected of diesels.

Where the E 300 would motor away from a standing start using electric power only, the auto-stop system would crank over the diesel in the E 250 using a conventional starter motor – with some of the attendant bump and grind encountered in a diesel four-cylinder called upon to fire up immediately. Not to say that the E 250 was as rough starting as some other auto-stop diesels from other prestige brands, but it was shaded by the smoothness of the hybrid's starting. So don't be confused, the E 250 is still a quiet and subdued vehicle for a diesel, but the added serenity of the hybrid would just about make it worth thousands extra tacked on to the purchase price, if that's important to E-Class buyers – and we think it is.

Steering in both cars provided a good balance of (electric) power assistance when required and acceptable feedback for a large prestige sedan. In fact the steering feel improved as speeds rose and lateral forces placed more weight on the tyres. The E-Class can be enjoyable to punt into corners, although in a non-threatening sort of way. Buyers in the car's target demographic needn't concern themselves that the steering and other elements of the car's passive dynamics might be nervy or startling.

Ride comfort in both cars proved agreeable and the two were very close in terms of peace and quiet inside. The E 250's ride and NVH – other than driveline-specific noise and vibration – seemed slightly better resolved than the E 300's. That's likely to be explained in part by the sedan body of the E 250 quarantining passengers from some additional road noise and exhaust.

But leaving aside any differences between sedan and wagon types, the clear winner here was the E 300 BlueTEC Hybrid. Diesels have gained greater acceptance from Aussie buyers in recent years – and the E 300 is a diesel too, of course – whereas hybrids still suffer from an image problem of sorts. Quite simply, however, the E 300 does everything the E 250 does – and better. We look forward to giving it a burl on local roads...