After the ActiveHybrid X6, another hybrid member joined the Bmw family: ActiveHybrid 7! The new vehicle, which will be showcased at this year's Frankfurt Motor Show, is based on the BMW 7-Series and sets new standards for performance and efficiency in the premium luxury class.
Under the hood of this beauty we find the upgraded twin-turbo, High Precision Direct Injection, V8 engine with a 3-phase synchronous electric motor capable to deliver 455 hp and maximum torque of 516 lb-ft (preliminary figures).
Power is transmitted via an 8-speed automatic transmission with the electric motor positioned between the engine and the torque converter. The new ActiveHybrid 7 can sprint from 0 to 60 mph in just 4.8 seconds while the top speed is limited to 150 mph. Also, the new car shows a fuel economy approximately 15% better than the 750i but the official EPA ratings will be available closer to the US market launch.
BMW 7 ActiveHybrid is a sports sedan that is able to deliver the dynamic driving characteristics expected from what is considered as the Ultimate Driving Machine. This is made possible as the BMW 7 ActiveHybrid uses a state-of-the-art approach to make sure that it has the best efficiency for its segment.
This model is a significant part of the BMW EfficientDynamics philosophy that utilizes technologies meant to improve driving performance while substantially lowering not just fuel consumption but emissions as well. This reduction in the fuel consumption and emissions is due to the hybrid technology employed. In general, when the combustion engine’s power interacts with the BMW 7 ActiveHybrid’s system, the savings potential offered by the technology is increased.
Since its V8 engine synchronizes well with that of its electric motor, the efficiency of its combustion engine is optimized regardless of the driving conditions. What the ActiveHybrid concept does is store all the energy in the high performance yet compact lithium-ion battery.
The BMW 7 ActiveHybrid uses an exclusive control unit to manage not just the charging of its battery but also to ensure that power is supplied to the electric motor and its electric ancillaries. In most standard vehicles, some of the energy is wasted as it is transformed to heat through the car’s brakes. The BMW 7 ActiveHybrid however is equipped with the Brake Energy Regeneration which can make use of this energy.
This same system has already been part of a number of the brand’s models that run solely on combustion engines. However, the BMW 7 ActiveHybrid has an electric motor integrated to it, serving as a generator when the car is coasting or when the brakes are applied. The power that is gained by the motor is then fed to its battery. Thus when the driver applies the brakes or lifts the foot of its accelerator, the Brake Energy Regeneration changes some the car’s kinetic energy to electric power which can be used for its on-board network.
It is when the car accelerates again that all the electricity is supplied to the network from its battery. This particular process means that the combustion engine is spared the work of transforming some of the fuel energy used to electric current and as a result, additional power is immediately sent to its rear wheels. The BMW 7 ActiveHybrid therefore has better acceleration even when compared to the 750i even if the extra power was attained without additional fuel consumption.
When the situation calls for the driver to use only a small amount of its brake force, the system responds by making sure that the electric generator’s drag is the one used. To get the additional stopping power, the mechanical brakes are only activated once the driver presses harder on the brake pedal. The shift from braking using the mechanical system to that of electric power and vice-versa is subtle enough that the driver is not even able to notice it.
This is all thanks to the Dynamic Stability Control which expertly balances the mechanical and electrical braking systems. The BMW 7 ActiveHybrid also offers two on-board networks that have been interconnected to ensure a more flexible energy management. It has an on-board 12-volt network that is supplied by the absorbent glass mat battery. There is also the lithium-ion battery which delivers 120 volts.
The lithium-ion battery in particular not only helps to start the engine but also aids in providing the electric motor with power. The electric power that the Brake Energy Regeneration delivers meanwhile supplies the two on-board networks. While the compressor for its air conditioner is connected to the 120-volt network, most of the electric-powered components get its power from the 12-volt network.
Adding to its flexibility is the voltage converter that links these two networks. It is the Brake Energy Regeneration that charges, and at the same time, maintains the two batteries. In addition, the energy provided to the 12-volt network is from the high-voltage network. The reason BMW decided to go for the lithium-ion battery technology is that it offers enough energy storage capability while only using a small amount of space. Compared to the 750i, or even the 750Li, the BMW 7 ActiveHybrid does not use any of its luggage capacity.
The reason is that the 120-volt battery can be placed under its trunk floor due to its small size. Aside from the size, the weight is light enough that it does not need more energy to carry it. This technology has allowed BMW to maximize the acceleration and storage capacity for a vehicle in this segment.
Compared to other hybrid sedans, it is the model that can accelerate the fastest. The battery has 35 cells which can give a total energy of 400 watt-hours. The control unit incorporated to it analyses the charge level constantly to guarantee that the battery can be relied on despite any conditions. The battery measures 37 x 22 x 23 cm, or about 14.6 x 8.7 x 9.1 inches. It also has a weight of just around 59.5 lbs or 27 kg.
Even with this size and weight, it still can deliver high performance level. Overall, it is larger in size compared to that of standard car batteries but it can be placed in the trunk floor and in the middle of its wheel arches. Protecting it is a special casing made of high-strength material. The location is ideal not just because it offers the battery better protection as it also ensures that the 50-50 weight distribution is guaranteed.
In addition, the placement of the battery also results in the luggage compartment having an estimated 13 cu. ft. of capacity, enough space even for two pairs of 46-inch golf bags. Though a hybrid, the BMW 7 ActiveHybrid has the state-of-the-art combustion engine. It uses the V8 reverse-flow engine that was originally introduced by the brand with the X6. This is the first V8 gasoline engine to have two turbochargers.
Placed in the V-section and in the middle of the two rows of cylinders, it delivers power all the way to the entire speed range of the engine. The shortest exhaust manifolds is a result of the compact configuration that allows for a spontaneous and more direct response of the engine. With 4.4 liters, the engine can give 440 hp of maximum output in revolutions from 5,500 rpm to 6,000 rpm. From 2,000 rpm and up to 4,500 rpm, the 475 lb-ft. top torque is preserved.
The engine is supplied with the right amount of fuel through the High Precision Direct Injection. There are the Piezo-injectors that have been put between the valves in its combustion chamber, ensuring that the combustion process is clean, efficient, and smooth. The engine is not only able to meet the ULEV II standards set in the U.S. but also the EU5 standards of Europe. The engine of the BMW 7 ActiveHybrid has been improved to meet its specific requirements unlike that of the 750i and the 750Li. For example, there is no alternator, starter, or even hydraulic pump. The air conditioning compressor does not even have a belt drive.
Even the cooling system was improved to meet the hybrid operation and thus gives outstanding power from scratch. The electric motor provides extra torque and thus increases its response. Unlike other hybrid vehicles available or other standard 7-Series models, the direct response to the BMW 7 ActiveHybrid’s accelerator pedal is remarkable. It can go from 0 to 60 mph in merely 4.8 seconds, making it comparable even with the fastest sports cars.
However, the maximum speed has been limited electronically to 150 mph. Its three-phase synchronous electric motor has been connected to its crankshaft and located in the middle of the torque converter and engine. The electric motor has a weight of 50.7 lb, about 23 kg. With its disc-like shape, the design makes sure that the electric motor can be fixed to the housing of the transmission. Maximum power provided by the electric motor stands at 20 hp with 155 lb-ft. of maximum torque.
When the electric motor is used with the Brake Energy Regeneration, it can generate an estimated brake force of 27 hp. Combining the combustion engine and the electric motor gives the BMW 7 ActiveHybrid a 455 hp maximum output with preliminary top torque measured at 516 lb-ft. In many cases, this amount of power would need an increase in the fuel consumption. Still, the BMW 7 ActiveHybrid can give this power but at the same time, it increases the fuel efficiency by around 15%.