Auto Design

The first application of the innovative BMW Active Hybrid technology is being introduced first in the luxury BMW X6. The integration of electric drive and energy recuperation and storage system adds some € 26,500 to the list price and, although the system does actually save fuel, it is not for economy reasons that buyers will choose the high performance BMW Active Hybrid X6.

They will do it do make a couples of clear statements: “I drive a V8 car because I like it” and “You see, I am concerned and I do my part to reduce the CO2 impact in favour of the environment”.

There are visual differences that tell that this is the Active Hybrid X6. The small badges and naming on the back, the sides and on the door sill but it is much easier to look at the additional bulge on the styling engine hood.

By choosing Hybrid cars, buyers do indeed support and contribute to research and development of a new technology that is in its early years.

Indeed, today, the new, high-tech batteries for greener cars are sophisticated, expensive and need to be handled very carefully. Engineers, technicians and drivers need some training and experience.

Like all innovations in the car industry (such as disk-brakes, ABS, ESP or GPS navigations system) they can only be afforded by top of the range models in their initial phase.

Forget the price, that many will be happy to pay, and let’s see if BMW is up to its leadership in innovative technology and efficient dynamics.

First, just see what the new Active Hybrid X6 does and how it performs, than try to understand how it does it. Well, apart my first embarrassment at trying to “start the engine” when indeed the “motors” were already in the go-mode and all I needed to do was to move my right foot from brake to accelerator, I immediately felt very comfortable and at ease with my sky-blue X6. The new BMW is faster and easier to drive than the regular X6 50i and its potential places it between the original and its V10 powered M derivative. After all this makes more price/performance sense.

Actually, I was amazed how quickly it would pull away from the traffic lights on Bal Harbour Boulevard and swiftly reach the 40 mph speed limit. The Head Up Display proved to be very useful to keep matching the car’s speed within the law. When your car accelerates so smoothly and so fast, you find yourself ahead of the traffic, you cannot “go with the flow” and you need to keep the speed under control, while looking ahead.

There is no extra noise, no vibrations or anything that gives you the perception this is a different sort of X6. Well, you would expect it to be quieter when the V8 is not running. It would makes sense. However, I cannot honestly say that there is no difference because you cannot hear the 4,4 litre, 300 kW (or 407 HP) TwinPower Turbo V8 gasoline engine (when cruising at legal speed in city traffic).

You have to look at the metres on the dashboard to see whether you are running on electric motors only or you are also using the engine, and at which speed this one is operating. Also you may like to know if the motor are boosting the V8 adding up to some 57 kW (and 180 Nm) to the engine (for a total of 357 kW and a record figure of 780 Nm) or, on the contrary, if the V8 is just recharging the battery pack. The display shows all this but beware: this may distract the driver.

The powertrain potential translates in acceleration time of 5.6 seconds to go from zero to 100 km/h and into a top speed of up to 236 kph or 250 kph with the optional Sport Package. The theoretical fuel consumption is 9.9 litres every 100 km, according to the EU5 test cycle, or 28.5 mpg imp according to the U.S.A. standards.

In real life and normal driving behaviour my best  figure was 12.2 litres. This is very, very reasonable for a car of this tonnage (some 2.5 tonns). The Active Hybrid systems does, inevitably, add some 200 kgs to the regular BMW X6.

Usually the NiMH 2.4 kWh battery (85 kg) is recharged when you lift the throttle and let the X6 slow down, or you are braking. In addition the electronic intelligent that masters all the energy flow to and from the two electric motors, also decides when some of the engine energy needs to be converted in electricity by the motors and charge the battery.

Why did BMW suggest a long itinerary in the Miami area (not too far from South Carolina where all BMW X5 and X6 are built), with just a short portion on the motorway is clear. The Hybrid technology delivers its best in urban areas with frequent stop, wait and go. When you wait the engine is not running. When you move ahead you can do the first couple miles (often from one traffic light to the next one) on the electric motor(s) only. They will take you to a speed of 60 km/h (37 Mph) if your pressure on the accelerator does not call for the V8 power.  And when you stop, the motors recover a great deal of energy. In these circumstance you really save a lot of fuel. On the contrary, there is very little fuel saving (or not at all) when you cruise at some 60 mph on the motorway.

200 kgs of Active Hybrid Technology.

The integration of BMW’s hybrid technology in their X6 calls for some 200 kgs of futuristic know-how and technology, the core of which is the Two-Mode Automatic Transmission, that indeed houses the two electric motors. In addition the systems include the power electronics, the high performance battery and a number of specific components. BMW and Mercedes-Benz have jointly developed and tested the new hybrid technology but in the implementation phase each company went along their own way. Mercedes-Benz will introduce their own development soon in their ML SUV. The main difference is indeed in the automatic transmission.

I do not know yet what Mercedes-Benz will be offering but what I have seen of the BMW’s two-mode, 7-speed unit is really impressive.

To learn more about it, I suggest you join me in listening to the presentation made by Hans-Stefan Braun, project manager of the Drive-train development. He does not pretend to be modest: “The BMW Active Hybrid X6 is the most efficient vehicle in its performance class. At the same time it comes right at the top of all hybrid vehicles worldwide in terms of driving dynamics through its overall system output of 357 kW/485 HP”, he says.

Among other modifications, the conventional starter, the alternator and belt drive for the a/c compressor and the hydraulic pump on the power steering have both been dropped. The main and secondary coolant circuit, in turn, have been modified for all-electric motoring, and a heat insulation plate protects the power electronics additionally from excessive temperatures.

The Two-Mode Active Transmission is the central unit in the drive system of the  Active Hybrid X6, as it ensures optimum interaction of the combustion engine and electric drive for maximum power and efficiency at any speed.

In its dimensions, the transmission for the permanent all-wheel drive car, is virtually identical to a conventional automatic transmission and is arranged directly in line with the engine. Although following the principle of an ECVT Electric Continuously Variable Transmission, the Two-Mode Active Transmission provides the mechanical connection between three planetary sets and four multiple-plate clutches in a configuration allowing the power split required for the drive power coming from the combustion engine and the electric motors in two transmission ranges and therefore ensuring unique variability in the combination of the two power sources conventional hybrid drive is not able to offer.

One of the two transmission modes is specifically for setting off and accelerating at low speeds, the second is for driving at higher speeds under optimum conditions. When setting off only one electric motor is activated at the beginning, enabling the BMW Active Hybrid X6 to drive under electric power alone up to a speed of 60 km/h or 37 mph. As soon as the driver requires more power, the second electric motor automatically fires the eight-cylinder power unit and  subsequently acts as a generator providing a permanent flow of electric power. The combustion engine is automatically

added to the power flow in accordance with the driver’s requirements and the level of performance needed, and is cut off by the electronic control unit when coasting at speeds below 65 km/h or 40 mph.

Power is transmitted by the Two-Mode Active Transmission acting as a seven-speed transmission operated by the driver by means of an electronic gear selector lever on the centre console. As an alternative to the automatic mode, the driver may also opt for manual selection of gears, shifting up and down either sequentially by moving the gear selector lever appropriately or by using the gearshift paddles featured as standard on the steering wheel of the BMW Active Hybrid X6.

Let’s stop here, otherwise you will blame me to convert this design blog into an engineer enclave. Only allow me to note here that The BMW Active Hybrid X6 is the first BMW SAV to come with  EPS

Electronic Power Steering for active steering assistance both when running on the combustion engine and in the all-electric mode.

It comes with integrated steering assistance related to road speed (Servotronic) and it significantly reduces the energy required in comparison with conventional, hydraulic power steering, since this electronic system is activated only when power assistance is really required or is desired by the driver. When driving straight ahead, therefore, the electric motor does not take up and consume any energy, thus serving to reduce fuel consumption to an even lower level.