Volvo's S90 sedan will come in for a round of mild updates, as evidenced by a lightly camouflaged prototype spotted during a recent round of cold-weather testing.

The changes will mirror those introduced this year on the updated 2020 XC90 and include a revised grille, new wheel patterns, and new color and trim options.

The most significant change will be under the hood, namely the introduction of mild-hybrid technology across the range. This is essentially a belt-driven motor-generator that can recover energy under braking and then store this for later use. On the XC90, Volvo said the system can improve fuel economy by 15 percent.

2021 Volvo S90 facelift spy shots - Photo credit: S. Baldauf/SB-Medien

2021 Volvo S90 facelift spy shots - Photo credit: S. Baldauf/SB-Medien

The S90 T8 plug-in hybrid should also benefit from a small bump in power and a bigger battery. In the 2020 XC90 T8, the battery size was bumped up from 10.4 to 11.6 kilowatt-hours.

Don't expect major changes in the cabin, though additional electronic driver assist features are likely.

The updated S90 will be launched alongside similarly updated versions of the related V90 and V90 Cross Country next year as a 2021 model. The changes represent a mid-cycle refresh for the current-generation S90 which arrived in 2016 as a 2017 model.