Thx to OP for review. Gas mileage is going to be relatively worse on the new V90 vs. an Old Swedish Steel 960 or 740 because the V90 is about 1000 lbs heavier and has all wheel drive. Plus the huge tires ( to carry all that weight) are a fuel mileage hit.
Just sticking a smaller engine in a car doesnt yield better gas mileage. My son‘s 2010 Volvo S80 with the 4.4L V8 gets about same MPG on highway as my 06 V70R with a 2.5L I5. Both are fast, heavy, have big tires, AWD etc. The price to pay for safety as they are stoutly built.
Just sticking a smaller engine in a car doesnt yield better gas mileage. My son‘s 2010 Volvo S80 with the 4.4L V8 gets about same MPG on highway as my 06 V70R with a 2.5L I5. Both are fast, heavy, have big tires, AWD etc. The price to pay for safety as they are stoutly built.