Here.
That’s in the CLA.
The GLA weighs slightly more (around 50ish kg), so it’ll be around half a second slower to 60. Half a second doesn’t translate to much when overtaking.
Basically, in the video, the car has two people – comparable to a GLA180 with a single one. Yes, the GLA is less aerodynamic, but at low speeds that doesn’t make mountains of a difference.