It depends largely on what your own priorities - but with a double garage, you will have more storage, and you will have a secure place to park both cars.
if you mean a door big enough for two cars 16/7 You can park a truck in a double door garage door!
It really depends on how big the garage is, as there is no standard size for a garage, although I will "guesstimate". Based on the width of two cars, and some allowance for space between the cars and the walls, I would say about 6 to 6.5 metres wide.
you can fit a total of 8 cars in the garage
cars
garage
I keep mine in my driveway. Other have garages, warehouses, parking garages, the side of the highway, etc;
a place you put cars
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Garage
In a garage.
garage.
In a garage