I'm not going to argue with you, if you drive like grandma, you are correct, and most likly won't notice a difference....but you're just not going to feel either of these effects driving a 4,000 pound luxury car.
V.D, don't worry about weight when choosing a size, it's not going to noticeably effect performance on these cars.
I do own a 4k performance vehicle, where it has been proven over and over, that larger, more heavy wheels greatly impede all performance aspects. Along with more break wear, more hub bearing wear, and a more heavy steering feel.
If you want to make your car slower, have fun, it's your car