No. You will need to create a separate transaction for each vehicle or edit the parking transaction so that the vehicle you are using is covered to park.
You can view your account balance in the statement page online or on the home screen in the app.
You can set your account to automatically top-up when a low balance is reached in the Account Settings page.
You can top-up your account through the app homepage or the top-up page online. Simply enter your card details and select the amount to top-up by to process your top-up.
As of February 2018, parkbytext will be introducing push notifications to app users. Push notifications will enable you to receive reminders that your parking pass is about to expire, at no additional cost.
Currently this is in the experimental phase of development, visible as an opt-in button in Account Settings on both the app and website. It will be live in the next version of the app due for release in March.