Except when they're not. I made the mistake of assuming the + and - buttons on the steering wheel of my Subaru had the same functionality as those on my Prius'

Except when they're not. I made the mistake of assuming the + and - buttons on the steering wheel of my Subaru had the same functionality as those on my Prius' steering wheel, which incrementally adjusts cruise control speed. On the Subaru, they are clutch controls. The result was downshifting into 1st gear going 70mph/100kmh+.