Is Mason getting an early Sweet 16 present? 

Kourtney Kardashian, along with sis Kim, took three-month old Mason to the Maserati car dealership in Miami on Thursday -- but it was Kim who left with a new ride.

While shopping in the lot, both Kourtney, 30, and Kim, 29, were spotted doting on the baby boy -- until Kim left the dealership driving a brand-new black convertible. (The sticker price on Kim's car? The new Maserati GranTurismo costs a whopping $136,000!)

"Mason and I went with Auntie Kimmie to pick up her car for while we are in Miami," Kourtney wrote on her blog. "She's driving the new Maserati Gran Turismo convertible. It's a ridiculous car and I think it's the first one in the US or something crazy like that!" (Kourtney also wrote that she was wearing a vintage dress and Tom Ford shades, and Mason was rocking a "little cashmere outfit from Neiman Marcus brand and Trumpette socks.")

So does her latest purchase mean Kim is thinking of joining sisters Kourtney and Khloe in Florida for the long haul?

"I love Miami sooo much!" she Twittered Friday. "Feels like home!"