I just got my Wisconsin license plate renewal notice and saw a new item - a hybrid tax for $75. Upon further investigation, I discovered that it's applied to hybrid vehicles with battery capacity not less than 4 kWh, to make up for loss of gas tax revenues. I've never had to pay that tax before despite owning the 2017 Prius since early 2017, so I was wondering what the capacity of the battery is. Does anyone know?