Audi’s new Q7 e-tron will be on sale in Europe by Spring 2016 and is presented as the world’s first plug-in hybrid model, with a six-cylinder turbo diesel-injected engine and four-wheel quattro drive.
Power and Performance
The electric motor produces 94 kW of power and 258 lb ft of torque. Meanwhile, the 3.0 TDI V6 diesel engine, delivers 258 hp of power and 442.5 lb ft of torque. The combination of these two units produces a power output of 275 kW (373 hp) and torque of 516.3 lb ft.
The electric only range is 34.8 miles, contributing to official US fuel consumption figures of 138.4 mpg. The 75 litre fuel tank allows for a claimed range of 869.9 miles. Performance is excellent, with 62mph being achieved in just 6.0 seconds before going on to a top speed of just short of 140 mph.
Audi claim the active engine mounts are another first in a diesel engine. Utilising electromagnetic oscillation coil actuators, vibrations are vastly reduced by introducing phase-offset counter oscillations. The engine mounts are always active when the combustion engine is running.
One effect of any plug-in hybrid is that the diesel engine can often be activated for short periods, even when cold and under high loads. This carries the threat of engine wear. To counter this, the Q7’s cylinder liners and piston rings are modified and a sensor is incorporated that constantly measures the quality of the oil. The engine control unit uses a dual-core processor for high computing performance.
The common rail injection system develops a system pressure of 2,000 bar.
The hybrid module is mounted between the engine and the eight-speed tiptronic automatic gearbox. Inside it are the electric motor and a clutch which is directly upstream of the torque converter. When the electro-mechanically actuated dry plate clutch opens, it disconnects the diesel engine from the drivetrain in just 80 milliseconds.
Battery and Charging
The lithium-ion battery is located under the luggage compartment. It comprises 168 prismatic cells arranged in 14 modules with 12 cells each and is liquid-cooled. It has a capacity of 17.3 kWh of energy at a rated voltage of 308 Volts. Multi-phase charging of 7.2 kW of power provides a full charge in less than two-and-half hours, or around eight hours on a household outlet. A smart phone can be used to control charging, in addition to heating and cooling.
Liquid cooling ensures that the battery and charging system remain within the required temperature range at all times. The power electronics are located under the floor panel of the driver’s area and has two key tasks: convert the direct current from the battery into three-phase current for the electric motor. And generate the 12 V electricity for the low-voltage activities.
The Q7 is provided with a universal charging cable that includes plugs for household and industrial
outlets and a graphical display also. A cable for public charging columns is also provided.
Audi claim a global first with the specially developed thermal management system with a heat pump. What would otherwise be wasted heat from the electrical drive components is made available to heats or cool the interior quickly and effectively.
Further energy savings can be made by using the standard MMI navigation to plan a route. Algorithms are incorporated to navigate in real time using up-to-the-minute traffic information and terrain information to decide when it is most efficient to charge. The navigation system, together with the cameras and radar sensors of the optional adaptive cruise control, generates a detailed image of the route up to 1.9 miles ahead. Speed limit and route signs, bends, roundabouts and intersections can all be processed and the driver advised as to when release the accelerator pedal via both the dashboard and by a single pulse from the active accelerator, against the sole of the driver’s foot.
The active accelerator has another function when in Hybrid mode (see the next paragraph), in that increasing the throttle pressure beyond defined point of resistance, the engine will become involved. Unfortunately this pressure point varies depending on the charge state, which will be less intuitive to the driver and so less useful.
There are four modes of charging available for the Q7. EV is electric only; Hybrid is fully automated; Battery Charge will continually charge the battery; Battery Hold only charges sufficiently to maintain the current level of battery charge. Starting any journey is always in EV mode.
When in Hybrid mode and travelling at less than 100mph, the car will coast as soon as the throttle is lifted. If any hazards are detected ahead, such as a slower car or town limits, regenerative braking will take place. All braking will be regenerative unless more effort is required than this technique will allow, in which case hydraulic braking will seamlessly take up the additional effort.
Chassis and Drive Train
The quattro all-wheel drive, which contains a self-locking centre differential integrated into the housing of the eight-speed tiptronic, can enhance stability by braking individual wheels as necessary. Up to 70% of drive can be made available to the front axle, with up to 85% available for the rear. Under normal driving conditions the split is 40:60, front to rear.
Compared with the previous generation, the new Q7 sits 50mm lower and is 100 kg lighter.
A central Electronic Chassis Platform (ECP) control unit governs all body control systems, regulating the operation of the each individual shock absorber within milliseconds. Electro-magnetically actuated valves vary the flow of hydraulic fluid. All this data can display the position of the car relative to the horizon in the lateral and longitudinal directions on a display in the MMI
Hill descent control is standard, as is Audi drive select (dynamic handling system), collision avoidance assist and trailer manoeuvre assist.