Volvo takes its XC90 to new levels of performance and eco efficiency with a high-power, plug-in petrol hybrid, says motoring editor Andy Russell.

Volvo always planned to launch a plug-in hybrid version of the second-generation XC90 and it's clear from the way it was designed from the ground up.

So there have been no compromises with the T8 Twin Engine, making it the only seven-seat plug-in hybrid with rivals sacrificing the third row of seats to put the drive battery under the boot floor.

In fact, the only obvious giveaways are a charging flap on the nearside front wing, badging and a charging and eco driving gauge in place of the rev counter.

How does it work?

The XC90 T8 combines the 320hp supercharged and turbocharged four-cylinder petrol engine – four pots is now the default for the Swedish car-maker – from the T6 driving the front wheels with an 87hp electric motor driving the rear ones.

They can work separately, for up to 27 miles on pure electric alone at up to 78mph, or together to give all-wheel drive when needed. With no need for a propshaft the length of the car, the drive battery is integrated into the chassis and housed in the transmission tunnel.

The driver can select different driving modes:

Pure – electric motor only.

Hybrid – default mode combining electric and petrol for optimum balance between performance and efficiency.

Power – electric and petrol for maximum performance.

AWD – electric and petrol for improved attraction.

Off Road – an electronically-controlled limited-slip differential function help negotiate tricky terrain below 25mph.

Save – retains battery charge for later use.

Charging takes 2.5 hours using a 16-amp fast charger, 3.5 hours with a standard domestic supply and six hours with a six-amp supply. Regenerative braking also trickles some charge into the battery with a 'B' position for the eight-speed automatic gearbox to double engine braking effect downhill and when towing.

With the XC90 the first Volvo to use the flexible scalable product architecture, which will underpin future models, there will be T8 versions of the new premium S90 saloon and V90 estate.

How does it drive?

Apart from near-silent running in electric mode, you're barely aware of the hi-tech powertrain switching seamlessly between electric and petrol.

It sets off briskly from standstill in electric mode up to urban speed limits and, with both power sources working together, put your foot down and 2.3 tonnes of SUV is fleet of foot, although it doesn't feel as quick as the figures suggest and gets vocal. Far better to back off a bit and enjoy the smooth refinement.

In hybrid mode, with plenty of battery charge, I could hover at 60 to 70mpg on the open road – on engine alone it halved. If you can do your daily commute on battery alone the T8 comes into its own.

The standard coil spring suspension can be upgraded to air suspension which enhances the ride quality but creates some initial body roll through fast corners.

Value

The T8 costs around £14,000 more than the turbo diesel D5 and £10,000 more than the conventional petrol T6 but that hasn't deterred buyers with the sales split, forecast to be 13% of XC90 sales, expected to rise to 20-25%.

Available in the same Momentum, R-Design and Inscription trim levels, the T8 also adds a powered tilt/slide panoramic sunroof, four-zone climate control, 12.3in active driver information display, crystal glass gearlever knob, drive mode settings and adjustable steering force, air-conditioning for the third row of seats and the ability to pre-set the cabin temperature before getting into the car.

Cabin and boot

While the T8 retains the XC90's standard seven-seat set-up, with plenty of space in the first five seats, it loses some load capacity but it's not going to be a problem as there is still up to 293 litres including underfloor storage to the window line with all seats in use, 671 litres in five-seat mode and a maximum 1,847 litres to the roof with them all folded flat.

And the new fascia is a big step forward in simplicity with a highly-intuitive new nine-inch touch screen tablet-style Sensus interface, to control heating, in-car entertainment, navigation, phone, car set-up, connectivity and numerous apps, doing away with lots of little buttons and switches.

Final say

The XC90 is a highly-innovative, highly-desirable SUV but the T8's technology, environmental credentials and performance take it to another level. But to justify the extra cost, even with savings in running costs and personal and company tax breaks, you need to be able to make the most of pure electric motoring.