At my wits end, school run

Turn up with snacks for her to immediately pick from.

Talk to her teacher and ask if she's showing any ND signs. IF she's autistic, she could well be masking all day, which is exhausting, and then letting it all 'go' when she sees you at the end of the day.

You to food - carbs if possible rather than sugar. I used to take jam sandwiches and then fruit to eat. Helped a lot.

Get into the car and drive off. She will soon be running after you.

Definitely take food.
Be very firm. Some things are non negotiable and politeness is one of those.

Yes, agree with this

And I'd also suggest the snack is "to keep you going until tea, as I expect you're hungry", not a reward / punishment. Food should never be linked to behaviour

I use to take food and let mine play in the playground for a bit. Unsurprisingly she has since been diagnosed as ND

DS2 used to be "lively" after school after the strain of behaving all day.

Would echo the PP who said get a snack into her but also that she could be decompressing and to speak to the teachers. Is she just over tired? What time is she going to bed/getting up?

Turn up with food!!!!
Don’t rush her off to the car, go really slowly, or even sit somewhere if you can. ( I used to sit mine on the school wall.) Dont ask how she is or how her day went….. just give her her favourite food and a big cuddle, and wait……. She’ll reset in her own time. It might take 10 minutes, but it’s worth it for the peace.

One of mine was like this. The rest were fine, once you know there's nothing wrong in school then I would probably put it down to tiredness. I use to bring her scooter to school, she loved her scooter and the minute she seen it she'd be more focused on that and forget to be so wild . There were days if I was driving that I would bring a nice drink and snack and I'd play her favourite songs in the car. I Found asking questions made her more angry, she just wasn't a talker, although now in her 20s she'd talk the hind legs off a donkey.

Are you sure she's happy at school? She sounds overwhelmed and like she's struggling to decompress.

I'd check with the teachers that there isnt something else going on, hiding being bullied, or struggling to keep up.

Sounds like she's getting overwhelmed in school and letting out all her feelings when she sees you.
I always found taking a snack helped, hanger is real! But also the snack is a distraction

Have you spoken to her teacher and asked if she's ok whilst there? Does she do this when someone else picks her up?
I'd try and do something to distract her from this, or try a reward chart, walk home well everyday and Friday you get a treat.

Id ask school if you can collect from the office, and read a book before you go home. Take the wind out of her sails, remove the audience.