I have the same issue and for a long time I could not figure out how the rain water is landing on top the car especially after I weather-stripped the top and sides of the door - until today when I just happened to open the garage door to clean the water mess on the car, the water came pouring through the sectionals of the door! Now it is simply not just the few drops of water that is the nuisance - if your car has some or lots of) dust the water drops create a messy look after the water drops on the car dry out - it looks really yucky on most cars and especially on a black car! If you want to go out and it is still raining, sure, the mess will be washed off but what if it is bone dry outside (sunny or not) - one is compelled to wash the mess off oneself or take the car to the car wash, unless one is ok with a messy looking car. This is quite annoying if this happens frequently as it does in the rainy season.

we had the same problem except worse because our garage is at the bottom of our steep driveway so the rain was rushing down the driveway and under the garage door making a huge pool in there. We did have a drainage channel in front of the garage but the water couldnt drain away quickly enough so it just overflowed, and all we did was install a french drain at the side of the driveway where the water could drain off to and it completely fixed the problem. By the way, our drainage channel isnt one you buy, it's just a concrete half tunnel that is part of the driveway so you could easily make one after cutting a small strip out

The tan knob at the top looks like the vacuum break. Here's what I would do at this point... I'd turn the water off at that shutoff, and then replace the entire assembly (frost proof sillcock). You can get the whole thing for $30 at big box hardware. Note that if you go this direction you need to unscrew the sillcock from the copper pipe while holding the copper pipe from turning (so two wrenches). Frost proof sillcocks come in various lengths - match what you have. Also match the end that connects to the plumbing (is probably 1/2" male threaded). While you are there at the hardware store you will need a small roll of teflon tape to wrap on the pipe threads before you assemble again to prevent leaks. You will also need a can of "Great Stuff" or similar foam. With the new sillcock connected and properly in place, foam the opening around the sillcock from the inside so it's sealed up and keeps out air, bugs and critters. You don't want foam outside, so the new sillcock should be positioned tight against the house. If foam does get outside, don't mess with it until it's dry... then cut it / clean it up.

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