Hm, tough question. One way to get a quick lower bound might be "what's something that uses the same general skills as driving cars, but is very different, and in how many ways is it different?" So if we use the same spatial skills to do knitting, and we say it's different from driving in a car in about 10 ways (where what we consider a "way" sets our scale), then there are at least 2^10 things that use the same skills as, but are different from, knitting and driving cars (among other bad assumptions, this assumes that two things being alike in some way is binary and transitive). If there are 10 domains (everything is approximately 10) like "spatial skills and spatial planning, basic motor coordination," then the lower bound would be more like 2^100.
If all of the things that humans can do are required for knitting and driving cars, than there are two things that humans can do, generalized to that level. If an AI could learn the hard way to drive and to knit, it would be able to do everything a human could do. I estimate that controlling vehicles is about four different skills by that definition (road vehicles, fixed-wing, rotary-wing, and reaction-mass spacecraft), but knitting, crocheting, and sewing are the same skill, and there are probably only two or three different skills that cover all of athle...
OK, so it covers only a few human occupations:
But the list is steadily growing.
Now, connect it with a self-driving AI, and your cab e-driver can make small talk, advise on a suspicious skin lesion, evaluate your investment portfolio and help you fix an issue with your smartphone, all while cheaply and efficiently getting you to your destination.
How long until it can evaluate verbal or written customer requirements and write better routine software than your average programmer?