When I bought my Impala a few months ago I got a lot of heat about buying a grandma car but when my friends drove it with the 200hp v6 0-60 in under 9 sec. they decided its a nice grandma car. I drive 180 miles per day, and get over 27 mpg cruising at 75mph. When I get out I am not stiff at all. Probably the most comfortable car I've driven. I am 6'4" and have plenty of leg room. I would recommend this car to anyone looking for a reliable, roomy car that performs well.
My favorite features are the aluminum rims, 27mpg at 200hp, lots of leg room, and a big back seat.
I guess there is always room for more horsepower and more speed, but thats the case with any car.