Volvo S60 and S90: High Performers
When it comes to horsepower, the Volvo S60 and S90 sedans are about evenly matched. The only difference comes with the Volvo S90 T6 AWD Inscription trim. This model will generally be able to hit a higher benchmark than other comparable models. Similarly, this model has a marginally higher horsepower RPM rating, but the difference is minimal.
Interestingly, the Volvo S90 T8 eAWD Plug-in Hybrid Inscription model can perform even better than the T6 AWD. This model with all-wheel drive can put out nearly 500 pound-feet of torque, which is nearly twice that of some of the other listed models.
In general, you can expect to see slightly better gas mileage in the Volvo S60 than the S90. The difference is minimal, and it is seen most in highway driving rather than city driving. If you're mostly interested in driving around Roseville, this difference would be pretty easily outweighed by other factors that might be more important. Realistically, the difference would amount to a four mile-per-gallon difference at most.
The Volvo S60 model has a fuel capacity of roughly 14.5 gallons, while the Volvo S90 has 15.9. When driving on the highway, this difference could realize itself by extending the range of your vehicle by about 45 miles. Practically, most people don't refill their gas tank when it's completely emptied, and the vehicle is a hybrid, so this 45-mile difference won't necessarily be seen that way by the driver. However, it may space out the time between gas stops if one is spending a lot of time on the highway.