How is the driving experience difference between 15 or 17 inches wheels on Gen 4?

I have a white/ gray 2011 five and a black/black 2016 4touring -- both came with 17". Drove many Gen 3's before I purchased -- The noise and ride difference was somewhat noticeable on the 2011 .. but very slight with the 17" bridgestone. The handling was noticeably better on the five -- I don't know if this was the wheels/tires or the different steering -- combination.

I really did not notice any difference with the 2016. I only drove a couple Gen 4's -- mostly to see if I still did not want the sunroof and if I could take the black interior. They had to find me a 4touring -- so I did not drive back to back.

We got mid to high 50's with both cars depending on drivers. I noticed a drop with the michelin tires on the gen3. I got 58mpg with the gen 4 the other day .. never hit that on the gen 3.

The 4touring is a nice combination. I never use the sunroof, but the extra light they bring into the cabin is need with some cars .. the pries has so much glass I don't think needed. Touring get the safety items without having to get the HUD or the parking assist.

 

I'll chime in here. We found my daughter a beautiful 16 Prius touring. I was surprised to find that it had 15 in Toyota alloy wheels on it rather than 17 in. I'm in the process of ordering snow wheels/tires and was considering the option of 17-in wheels or possibly even a compromise at 16-in wheels but in the end I'm going to stay with 15 in. Fortunately, my daughter is a very slow, conservative, safe driver and in the end, the huge sacrifice in MPG and ride quality just are not worth it. I just ordered some rather inexpensive wheels and Bridgestone blizzak in a 15-in, I guarantee that's going to work great!

 

Everything I've read indicates that the larger wheels ride rougher.
The sidewall profile, the second number in the 195/75R15 (example) is a percentage of the width - the first number, in millimeters.
There is only so much room in the wheel well. If you were to try to match the sidewall percentage on a 17" to replicate the 15", you'd end up with a much larger diameter tire (2") and your speedometer would need adjusting assuming the tire fit in the wheel well. So, lower profile tires are fitted on bigger rims.
The tire is an integral part of the suspension of the vehicle. When you reduce the amount of sidewall, you remove material. That material flexes with impacts and cushions the ride.

And 15" tires are cheaper, too.