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Volvo XC90 T8 plug-in hybrid 7-seater SUV delivers 59 MPGe; more powertrain details

8 December 2014

XC90 T8. Click to enlarge.

Volvo Cars’ new XC90 T8 plug-in 7-seater hybrid SUV delivers total system output of 400 hp (298 kW) and 640 N·m (472 lb-ft) of torque combined with ultra-low emissions (59 g/km) and high fuel efficiency (2.5 l/100km). The fuel economy according to the US driving cycle is 59 MPGe. Volvo earlier this year had suggested the fuel economy rating on the US drive cycle would be around 60 MPGe. (Earlier post.)

The XC90 T8 builds on Volvo’s new modular Scalable Product Architecture (SPA) platform and successful Drive-E gasoline powertrain. The XC90 T8 can accelerate from 0 to 100 km/h in 5.9 seconds. The car has five different driving modes that deliver a range of performance and efficiency-enhancing characteristics. Using either a scroll wheel on the centre console or a touchscreen on the dashboard, drivers can choose from:

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• Hybrid: This is the default mode, suitable for everyday use. Here, the vehicle will automatically alternate between drawing power from the 2-liter, 4-cylinder Drive-E engine and the electric motor to deliver the best overall fuel consumption.

• Pure electric: In this mode, when the high-voltage battery is fully charged, it serves as the car’s sole energy source, powering the electric motor over the rear axle. The XC90 T8 has a range of more than 40 km (25 miles) using just electricity, which covers the total distance most people drive in one day. With the regenerative braking system, this mode is efficient in the stop-and-go traffic of city environments. If more power is needed, the Drive-E combustion engine starts up automatically.

• Power mode: Here, drivers get the combined performance of the combustion engine and the electric motor. On start-up, the SUV takes advantage of the electric motor’s superior response and instant torque curve, while the combustion engine gets up to speed. This combination offers better torque at lower revs, equivalent to that of a large displacement engine.

• AWD: This mode offers constant all-wheel drive on demand. The advantage of being able to select AWD manually is that the driver can use it when needed, or choose to save energy for later.

• Save: If the battery is charged, this mode allows the driver to “freeze” the battery level and save it for later use with Pure Electric drive. On the other hand, if the battery is low, the driver can use the combustion engine to charge the battery to a certain level for later use with Pure Electric drive.

Powertrain components include:

• Drive-E engine. A specially modified version of the 4-cylinder Drive-E gasoline engine is under the hood. The Drive-E engine is enhanced in the XC90 T8 by a supercharger and a turbocharger for a total power output of 318 hp (237 kW) and 400 N·m (295 lb-ft) torque.

• Automatic gearbox. The 8-speed automatic gearbox has also been specially adapted for the hybrid: shift-by-wire technology allows drivers to control the transmission electrically. A larger oil pump provides the necessary lubrication during electric drive and enables quicker pressure build-up when seamlessly going from electric to combustion drive.

• CISG. The crankshaft-mounted starter generator (CISG), located between the engine and the gearbox, performs three functions: it is a powerful, 34 kW starter motor that allows the car to go from pure electric drive to combination combustion drive seamlessly, so drivers can experience the car’s engine and electric motor as one unit; it is also a powerful electric generator; and finally, it acts as an electric engine booster, working with the supercharger and turbocharger when extra power is needed, providing up to 150 N·m (111 lb-ft) of extra torque.

• Battery. The high-voltage (270–400V) battery delivers 65 kW of power. Volvo placed the battery centrally in the tunnel of the car to overcome packaging issues. There are several advantages to this position. For example, the battery does not impact the amount of available space inside the car. Furthermore, the battery placement gives the SUV a low and central center of gravity, making the XC90 T8 easier to handle and safer to drive.

• Rear electric motor. Delivering 82hp (60kW) and 240 N·m (177 lb-ft) torque, the large electric motor sits on the rear axle and drives the back wheels in electric and power-boost modes. The rear placement allows for a larger motor, which is useful for following stop-and-go city traffic rhythms. This placement also makes efficient all-wheel drive possible because each axle has its own power source.

• Two-step braking system. The XC90 T8 blended braking system partly uses brake-by-wire technology to recover and transmit energy back into the car, either to recharge the battery or for immediate use. The system is also equipped with a unique stability function that controls the amount of energy that may be safely regenerated.

• Cooling and climate system. The cooling system is composed of two extra circuits. The first cools the CISG and the large electric motor on the rear axle, while the second cools the battery in one of two ways: either passively, via the radiator, or actively through integration with the car’s climate system.

• Pre-conditioning. For convenience and efficiency, drivers can pre-condition the XC90 T8’s drivetrain, battery and cabin, either directly from within the car or by using the Volvo On Call mobile app. This ensures that, whether it’s freezing or hot and humid outside, the car will be heated or cooled as necessary and ready to go by the time the driver enters. Pre-conditioning can be done while the car is plugged in, which is beneficial from a CO₂ perspective since it ensures that the battery will last as long as possible in Pure Electric Drive mode.

December 8, 2014 in Hybrids, Plug-ins | Permalink

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