Car hoist research is the fundamental step before selecting a suitable hoist. As these hoists are built in, they are expensive to change out, if your selection process is flawed.
It is not quite as straightforward as measuring the width of your garage at the narrowest point as you also need to take into account other obstructions. Things like garage door openers, cabinets, stairways, benches, door tracks and the like. Any obstruction that is going to limit your access squarely onto the car hoist needs to be identified.
An example of this may be that you have an obstruction such as a protruding wall that limits your direct access to the hoist area. A 4 post hoist may prove difficult to drive a vehicle onto as the front pillars of the hoist are limited in width. Then if this is the case, you need to look at a 2 pillar car hoist that will allow you turning room between the obstruction and the hoist pillars which would be set back further than a four post hoist.
There is also another option that should not be ruled out, and that is consider putting the car hoist at a slight angle that would assist the ease of driving the vehicle onto the lifting platform. Always consider ease of access as this is what will determine the suitability of your choice of car hoist. Select a hoist that is difficult to get a vehicle onto will wear you down and frustrate you no end, not to mention any probably light panel damage that will inevitably result in shuffling a vehicle around in an attempt to get it on the platform.
Measure the depth of your garage, not from end to end but from clearance of obstructions at each end. You need to assess that length of the parking lift and be assured that there is enough working room around the hoist and that it is safe and clear. The hoist needs to have clearance all around it so as to allow personnel working in the vicinity room to work unobstructed. Take into consideration the width or any benches and allow working room on top of that again.