A few weeks ago, I sat in the passenger seat of my little car and held on to my hat. Beside me sat my stepdaughter Gabrielle with her hands on the steering wheel, looking like she was about to burst. It was her first lesson in learning how to drive standard and we were in the parking lot of a nearby golf course.

“OK, now as you lift up — easy does it — on the clutch, you press on the accelerator,” I said, mimicking the movement with my hands to underscore the point.

“See what I’m doing here?” I added, performing the movement again, looking like a confused traffic cop.

She looked over politely, though I could see the thought surfacing in her I-scored-a-32-on-the-ACT-while-still-a-freshman head: “Relax, old lady. I got this.”

“OK, give it a try,” I offered, trying not to hold on too tightly to the door handle.

I think we all know what happened next. The car performed its version of a retch, ka-lunking forward, pausing for breath, and ka-lunking again, its metal throat grinding painfully on itself.

“Whoops,” she said.

“It’s OK,” I said after the car had stalled. “Try it again.”

So there we stayed, lurching forward as the sun set over the golf course, the smell of ruined transmission fragrant in the air, my instruction eventually reduced to, “OK, just watch my feet.” Every once in a while, I would look over and be overcome by how surreal it was to see her in the driver’s seat. But mostly we just laughed, doubled over, as concerned golfers looked over, wondering if we needed help until we waved them away and explained our antics with one word: “Stick.”

I have to say, it was one of the greatest days of my life as a step-parent.

As you’ve likely guessed, Gabrielle has turned 16, a milestone that I think has taken all of her parents by surprise. As her mom so poignantly posted on Facebook on the day of Gabrielle’s birthday: “It happened. I blinked. She’s 16.” Reading that instantly made me cry. Because where were Blankie and Felicity? Where were her Polly Pockets? Where were her hair bows? And where, bless it, was her retainer?

Gabrielle, on the other hand, has taken the birthday in stride. She’s deep in the planning stages of her Sweet Sixteen party, which she’ll host with her best friend Emily this Saturday. She’s keeping her eye on her finances in anticipation of the gas money she’ll need for future. And she swiftly passed the written portion of her driver’s test.

And who can blame her for her joy? Is there anything better, in the end, than turning 16? I so keenly remember the day I passed my driver’s test (by the skin of my teeth). Getting into my Nissan Micra afterward and being able to go anywhere I wanted? Boy, the flavor of that freedom was sweet, sweet, sweet. I didn’t have a stereo so I plunked a boom box in the passenger seat and listened to Paul Simon at full blast. I packed as many friends as I could into the little hatchback (my little brother Matthew reduced to the trunk) and drove them all home after school every day. I pulled in at the drive-thru at McDonald’s and had McChickens and French fries and hot-fudge sundaes. I never gained an ounce.

More than that though, it was the feeling of having finally arrived. I don’t know that Gabrielle has suffered as much as I did, but all I wanted throughout my childhood was to be older, to shed youth, to be able to Wear Lipstick and Go To The Beach and Have A Boyfriend and Get A Job. I may have frittered away some of my younger years dreaming of those things, but once I turned 16, boy, not a moment was lost on me that all of that was now possible.

And on Saturday, when we celebrate Gabrielle’s birthday with an over-the-top extravaganza, and she’s dressed in high heels and lipstick and she’s dancing on the dance floor and letting us see moves we didn’t know she had, I know I’ll see that same look of pure freedom, evidence of that firm arrival. So I’ll think of that little afternoon we shared when she was learning how to drive in the parking lot with the worried golfers. And I won’t cry because I’m a big girl. But I will take a big sip of champagne and silently toast to this kid who has been the best thing that has ever happened to me.