For anyone wondering, assuming linear acceleration that's roughly 1 g. In a rear-facing seat, that's 1 g eyeballs-out, which should still be perfectly safe for the child, but possibly not for the cleanliness of the seat.
Also, basically any boring passenger car can brake at or slightly above 1 g.
...and if you're wondering what 1g eyeballs out feels like, you can always try looking at your feet.
Shouldn't it be actually ~1.4142g at a 45 degree angle?
You're proposing that gravity is stronger in a direction other than the one straight down to the center?
I think they’re referring to the fact that in the Ferrari, you’d experience both 1g eyeballs out plus the 1g of normal gravity, for a total of sqrt(2) at 45 degrees, when compared with looking at your feet producing 1g down.
Maybe if the acceleration is smooth enough, but the sudden appearance of a new g yanking your head to your chest might be dangerous for a baby.
A performance Tesla can also accelerate to 60 under 3s, and with proper warning to hold their heads, my young kids love the rush.
That's a great way to have to change a diaper. Or your pants.