The Volvo S60 models don't stand out among sporty compact sedans; and with the recent introduction of turbocharged four-cylinder engines from Mercedes-Benz and BMW, the S60 is now looking near the back of the pack with respect to fuel economy.
With some significant changes to the base five-cylinder engine in the 2013 Volvo S60 T5 models this year, we don't yet have EPA numbers; but last year's base S60 T5 with front-wheel drive was the best of the lot, at 23 mpg city and 30 mpg highway. All-wheel drive models typically come in a bit lower.
There's actually no penalty for the higher performance you get in the R-Design versus the T6. Both achieve 18 mpg city and 26 mpg highway in EPA testing, for 21 mpg combined.