Another Georgia Tech grad / software developer here...
The problem with your plan is that modern car repairs are massively computer based. There is proprietary software that costs like $100k or more for each model and so only dealerships and specialty garages actually invest in each particular software.
My husband is very very mechanically inclined and has earned all of his money from cars and motorcycles since he was 18, and he is now 39. We have a 2006 Dodge Sprinter Van, so when he needed to do some troubleshooting he had to drive it to 3 different Dodge dealers before he found one that actually owned that particular software (since it is a rare model).
He should have tried the Mercedes dealer. The Sprinter is actually a rebadged Mercedes.
One thing to keep in mind is that sometimes these expensive manufacturer-specific computer diagnostic tools have much cheaper 3rd-party equivalents. For example,
this third-party tool is available for VWs.
These electronics can also make things easier for mechanics. If something is misbehaving and you can't see why, hook up a scan tool (which is standard across all cars post 1996) and see if there are any relevant codes or unusual sensor values.
They're really only "mostly" standardized. There is a baseline level of functionality that any generic ODB2 scan tool will read, but modern cars have a lot more than just the ECU (google "CAN-BUS" for more info). On a VW, for example, a generic scan tool will be able to read engine trouble codes and sensors, but the VW-specific tool I mentioned above will be able to do things like reprogram the radio, control the door-lock-and-power-window module, etc. I think you can even do things like change transmission shift points and engine mappings (i.e., how much fuel to inject at each combination of RPM, gear, throttle position and airflow) using the right software.
You could just join a forum for the car(s) you own (like PriusChat.com) and keep an eye out for common problems. When your cars have an issue (broken parts, or time for a brake job) then you could consult the forum gurus, YouTube videos, online manuals, and other references for that specific job.
It's like learning a programming language only when you need it...
This is good advice. In fact, it even goes beyond that: the VW forums I'm a member of have "get-togethers" that are half-social gathering, half-wrenching session. I remember that at the first one I went to, some of the gurus swarmed over my car, replacing my worn vacuum lines, re-tensioning my timing belt, and diagnosing a failing dual-mass flywheel almost before I even had a chance to ask for help.
I've seen people get their transmission swapped from automatic to manual at a car club get-together (without using a lift or any other big fancy tools, either!).
I agree with your comments, OP, about wanting the structure* of an actual class---I've always found that very helpful and necessary in my own learning. I think a lot of people overrate the ability of people in general (and themselves in particular) to learn things on their own (and so I'm kind of skeptical of things like MOOCs).
Having taken and passed several MOOCs, I would argue that they do have all the structure of an actual class. (As long as they've got actual deadlines instead of being 'self-paced,' anyway.) You have to be motivated to watch the lectures and do the work, of course, but that applies just as well to a traditional in-person course.
That said, I think something like auto repair could be better learned hands-on.