28 years old. Went to HS during the fiscal crisis, and we were lucky if we had heat, let alone these “driver’s ed classes” of which you people who went to rich kid schools speak. 
Now, to be fair, my brothers both got theirs around 16 and 17 and drove junkers around (parents have never bought any of us a car, last name not Rockefeller!) but they were much more Yonkers-oriented. My friends and I (none of the guys I ever dated had cars) liked Manhattan; we took the subway and ended up in places where you could have spent a) two hours or b) two week’s after-school-minimum-wage-jobs salary to park the things. So, screw it.
I then went to college in the exact city that you need a car even LESS-Boston. It wasn’t until I graduated and was living in Cambridge for a few years that I decided I should have one for road trips. My first lesson was to pull out onto traffic on Broadway and–this’ll be a hoot for people who know Cantabrigian geography–drive nearly to Harvard Square, right on Oxford, to Mass Ave, through Porter Square, up to Alewife, over to Mem Drive, back down past Harvard Square, then up River to Prospect to home. Those prosaic words cannot convey the dodging of cars, busses, trolley-busses, bikes, and 17th-century-era streets laid out by cows and shephards that I had to navigate while still trying to remember what the bigger pedal did.
Got the license and then didn’t drive for five more years, it being just a harrowing ordeal, until finally I moved back to NYC, and a couple of years ago went on a solo road trip to Williamstown, MA because there was a play I wanted to see up there, dammit. Trip up was fine, play was incredible, and then I had to drive back along the Thruway during a storm that resembled a car wash. Made it and haven’t been scared since, although I still haven’t driven midtown Manhattan traffic (I have skittered across Manhattan from the Bronx to the GW Bridge, and once picked up a friend’s car for her from Lincoln Center area and ran right over the Henry Hudson and over to Jersey. That’s it. They be crazy down there.)
And oh yeah, does my late Grandma get the prize? She was 68 years old when her husband’s Parkinson’s got too bad for him to drive; she just up and learned and drove as fast as she could whenever she liked. 