As you live in Texas you have the heat as an additional condition benefit. The heat taxes your body more then a air controlled fitness club and you body has to overcome the heat as well. trying doing your workout outside.
This has been studied and found not to be the case, in fact, if you are training for an activity top be performed in a cooler climate, it is a training distractor/impediment.
Also, VO2 Max is a very poor predictor of work capacity, unless you plan on running on a treadmill, which is typically how it is measured. There is somewhat of a correlation, but it is weak and hardly predictive
