Depending on the app and the size of the object, the whole process of scanning takes from seconds to minutes or hours (if you have a building to scan, for example).
If you need to scan with a mobile phone, then with the ones like SONY Xperia XZ1 it is totally free, because there is a built-in app, but if you have an average Android or an iPhone, you need to download an app like Scann3d or Polycam and scan your object using their tools. Sometimes you need to pay for a subscription, about $10 per month, or pay for exported projects: from $1 to $10 each.
Though it’s more complicated, you still can shoot yourself from different angles and download the pictures into the app.
Depending on the size of the car, it may take about 30 mins, because you will need to thoroughly scan every single unit to make the whole picture as realistic as possible.
It may take from 10 to 30 mins, depending on how clear and detailed you want this 3D image to be.