I've been using aCar for a while. I just factory reset my phone to start afresh and did a new install of aCar. My first step was to add my vehicles again, but after entering only the name of the first vehicle and trying to save, I cannot due to validation errors.
If you are on aCar 5.0, please enter all of the required fields in the Add Vehicle screen. You will need the name, type, year, model, and submodel entered to save.