BART takes 2x the time station to station. Try it out right now.
The time is 1256 as of the time of this comment.
SFO International to Montgomery St. Station: Earliest arrival is 1346
Driving: Earliest arrival is 1323
My experience is that the car takes ~6 min to arrive to pick you up for Uber. You can call it earlier, but assuming you call it when you arrive and then wait that's 1322. You lose 23 minutes to BART.
And that's BART station to BART station. Change it slightly, like to my home near Caltrain and it's pointless. The cost in time is way more than $25.
