Sitting in a ton and a half of plastic and electronics, digital electronics to be exact isn't exactly my idea of soothing for the sole. Knowing the two prii in the drive way are paid for, well, that does sooth my sole
I had to mentally "shift gears" when learning to drive our Prius in a fuel-efficient manner. Keeping it in the Eco zone and maximizing regenerative braking forced me to adopt a much more smooth, laid-back driving style, and I do find that to be calming. Long distance drives feel less stressful, possibly in part because I am not passing as much and do not have to be hyper-vigilant for upcoming speed traps. However, changing back to a 5-speed sports car or pickup truck with a v-8 does result in some odd discontinuities!