Multiple Symfony form types, all for same object, validate at once by faking submission - symfony-forms

Question

I have several FormTypes, all for the same entity type (Car, e.g.), each handles a different aspect (DoorsTyoe, EngineType, TrunkType, SeatsType). When the user has walked through all these forms, on different pages, I want to check before finally saving the results, once more all FormTypes.
So the idea was: Create a new FormType CarType, put all the different pieces on it (DoorsType, EngineType, ...), "fake a submit" and get the errors. But when I want to add the different "sub-forms", I cannot add them without specifying a "child name" for them. Is there any way around this? Right now, I create an array with all the child names, and have a the car object in a separate key:
public function buildForm(FormBuilderInterface $builder, array $options): void
{
$builder->add(
'doors',
DoorsType::class,
[
'getter' => function ($data, FormInterface $form): Car {
return $data['theCar'];
},
'setter' => function (array $data, Car $submittedData, FormInterface $form): void {
// just throw away what we get.
},
],
);
// And so on for EngineType etc.
}
Then I call this with:
$fooData = [
"doors" => "PLACEHOLDER",
"engine" => "PLACEHOLDER",
"theCar" => $car
];
$form = $this->formFactory->create($formType, $fooData, [
]);
$form->submit($fooData, true);
$errors = $form->getErrors(true, true);
dump($errors);
return $form->isValid();
My issue is the crazy structure with the $fooData array. I would prefer to work on $car only. When I change the DoorsType etc. to unmapped fields, the getters are not called so I assume they will not work at all?
Somehow I am missing a point...