Volvo has recently streamlined their powertrain lineup to just one engine offered in three variations. This engine is a 2.0-liter turbocharged four-cylinder, and can be had just turbocharged, turbocharged and supercharged, or the latter along with an 87-hp electric motor. Volvo calls them T5, T6, and T8, respectively. All are backed by an eight-speed automatic transmission.
Unsurprisingly, the tamest T5 powers the base model, and is also the only motor available with front-wheel drive. Making 250 hp, this variant keeps the S90's price down but its persona isn't befitting a $50,000 luxury car. Compared to the T6 and the T8 – and especially when compared to the competition – the T5 is lacking in power and refinement. There's a constant nagging feeling that this engine belongs in a lesser car, not in something with grandiose aspirations of taking on the established luxury cars.
The T6 improves things with 316 hp and 292 pound-feet of torque. It's only available with all-wheel drive, and we think that's a good thing – front-wheel drive in such a large and stately car doesn't jive well with us. Luckily, the additional power of the turbo- and supercharged T6 masks most of the deficiencies of the T5. Passing can be done authoritatively, and the rather coarse nature of the T5 is more muted here. The extra juice and additional refinement offer a strong incentive to spend a bit more and move into a T6-powered S90.
New for 2018 is the high-zoot T8. In this guise, that 2.0-liter four is buried under a turbocharger, supercharger, and an electric motor. The whole setup is good for 400 hp and an impressive 472 lb-ft of torque, and manages up to 21 miles of all-electric driving range and fuel economy of 23 miles per gallon city and 33 mpg highway. Unfortunately, we haven't driven this technological tour de force, but are looking forward to determining if it's as good in person as it looks on paper.