Vehicle weight: base Prius vs. high end packages

I don't have a definitive answer for you, but do have a link to what Toyota says about II-Y weights so you won't have to look it up.
Toyota Prius - 2010 Performance & Specifications
It's obviously not correct because it list all 4 models as the same exact weight to the pound.

I have seen 65-80 lbs claimed for the sunroof plus solar array but don't have the source handy. 80 lb on the roof would feel like more than 80 lbs when maneuvering.

 

There is no way she's able to tell the lightness of the lesser items. If you want to prove this to yourself once you figure out how much any options weight go and throw that into her trunk and have her go for a drive and ask her again if it still feels lighter. She'll say yes, you'll say look at this weight in the trunk she's go "hmm".

 

Being as you own both, you could always take them to a local truck scale and get them weighed, we'd all know for sure then...

 

There are stickers on the frame that you can see when you open the drivers door. That should tell you how much each weighs. If you would like I can check my vehicle weight tomorrow for the II. I'm curious what the leather and sun roof weigh.

The difference in fuel consumption should be minor between a II and IV with sun roof. It should be the same as having a passenger versus just the driver, or a much heavier driver ;-). The sunroof will cause more drag when opened, but might require less air conditioning if it keeps the car cooler when parked. The heavier wheels and higher rolling resistance cause a small decrease in mileage with the V. That is quite a reward for working just one summer.

 

You can take two cars that are identical models and identically equipped and they may feel different.

For instance, differences in wheel alignment can effect how quickly a car responds to initial steering input. A quicker responding car will feel lighter to most drivers.

 

She may be running hers in Power Mode while you're running in Eco Mode! I know I can loose what feels like a couple hundred pounds with the press of a button!

 

I doubt many people can even tell when they have a 200lbs passenger in the car... So the weight difference from 80lbs of the options will be very difficult to feel.

Perhaps she is used to driving the loaded up Prius full of passengers compared to her new "II" all alone.

3 male passengers in my Prius III makes a big difference in handling, braking and acceleration.