I'm going to guess that the garage is detached from the "main house"? If it's not then all you'll have to worry about is your house mates... and they can usually be bribed with beer [etc.]
Unless you're planning on listening at 110+db SPL through many of the wee hours of the morning it shouldn't be a problem.
Air [as in the space between buildings] is a pretty poor conductor of sound... so, if you have a good amount of air space between you and the neighbors you probably won't have a problem.
If there is a problem then you can address it then... but again, if you're using 'near field monitors' [even with a sub] it really shouldn't be a problem unless you're doing a bunch of live tracking [with instruments in the 110+ range].
Check the city's noise ordinance... chances are you can be at least 80db at the property line most of the night... certainly until 10pm. So... if you need to do things like "loud guitar" overdubs, start around 7p, go until 9:59p and then either switch to recording acoustic GTR, or DI bass, etc. If you need to do drums or extended tracking sessions... it's why weekends were invented.
If you're not recording live instruments, then you really have no problem... the walls will knock down a minimum of 20db [if they're made like crap... more if they're made well] and you should be within the limit of the law without a struggle... from there bribery will keep you on good terms with the neighbors or working at a lower level will put you in a place where they don't know you exist.
The problem with apartments is that your floor is your neighbor's ceiling... unless you have a 3 family garage chances are pretty good you're not going to have the same issues you might have in an apartment... rendering the "vocal booth with no HVAC system" a moot point as it will most likely be unnecessary.
You may very well have bass shell acoustic issues but those can be dealt with like any space's internal acoustic properties can be dealt... if all you're worried about is the neighbors... wait until there is a problem before you drop a boat load of coin trying to solve a problem that may very well not exist.
Make sense?