Normal width of a single car garage is 8' feet. Normal width of a double car garage is 16' feet. These answers are for doors typically found in the USA.
Typically, a 2 car garage minimum width is 24'. This said, there is no reference to minimum widths for garages in the IRC building code that I can find.
The average with of an one car garage is 12 feet. Many people will want a few extra feet of width for storage.
The standard width of a double car garage is 20.5 feet. That is a big enough size to fit a large sedan and a truck inside.
20 feet
The standard double car garage door is 16' wide x 7' high. A two car garage should typically be a minimum of 20' wide (inside) to allow the doors to open. 22' to 24' width is preferred.
Yes my garage width is 2" too small to drive in. With mirrors folded I have 2" clearance each side
Generally 8' or 9'
You'll need to get a nonstandard garage door (not single-car width), so that may be very hard to find.
Sixty feet is a good size width for a 3 car garage. This comes from the Illustrated Guide to Tactical Drawing: How to Determine Floorplans. It calculates the size of the cars with doors open and adequate space to walk between vehicles.
8 or 9 foot, either one is common.
Garage Mahal - 2009 Car and Driver Garage 2-10 was released on: USA: 18 June 2010