Tandem garage is different compared to the traditional style garage. In General, Garage is a place which is used for car parking, basically this enclosed area with a shutter protects cars from theft and weather hazards. Now a ways, modern homes are designed with multi-level garage structures, in which cars are parked along side the storage cabinets and shelving area.
A basic tandem garage is built according to the space available for it, it can be wide enough for parking one car and long enough for parking two, three and four cars all at once. Basically, you can park cars in front of each other rather than side by side. Due to the limited space available on modern homes it is not plausible to construct big garage and sacrifice the space which can be used for making additional rooms and bathrooms in the residential areas. This is not logical to give a lot of space to the garage especially if it will cut down the space in home. If you have two or more cars which need to be parked under the same roof it is advised that you design a two, three or four cars tandem garage plan for saving the space. Basically, the structure and design of the garage will be long or possibly narrow, but you would be able to park the cars in longitude positions rather than in horizontal positions. If you get some space later on you can extend the garage for increasing the width.
Whether you construct a four car or two car tandem garage the width will be of standard size which can accommodate a nice sized car easily, however, there should be some depth in the garage plan and at least one door for entering or retrieving the cars easily. The only draw back would be that you would have to unpark the car which is parked near the rear garage door first for moving or driving the one which is parked inside the area.