Can you save your game and change your clothes in add-on houses?

I noticed that modders don't do concept cars and those who do are usually modders who aren't really good in doing mods. No offense. The cars usually crash and have bad interior and exterior quality.
I will like if modders can invest more into making concept cars.

Some I would like to see are;

BMW Vision Next 100
BMW Vision M Next
Mercedes Benz Vision EQS
Mercedes Benz Vision AVTR
Mercedes Benz Biome
Rolls Royce EX103
Audi R-Zero
Audi Locus
Bentley EXP 100 GT

I wanted to know if it is possible to save your cars in the garage in the add-on houses and also save your game there and when next you load your game if it will still be there. I downloaded two and I couldn't sleep on the bed to save my game. Thanks.

@Reyser Okay thank you.

Is there a mod to make the steering wheel of a vehicle turn fully just like in a real car when in first person view in a vehicle? Thanks.

I was wondering if someone could please do an add-on car mod for the Alfa Romeo Gloria Concept. Thanks.

@ReNNie Thanks so much. It worked.

Please I really need the following cars. My version is not the updated version so I don't have them. Can someone please help me extract the cars from their game, zip them and send them. Thanks a lot.

These are the cars:

Invetero Coquette BlackFin
Enus Stafford
Grotti X80 Proto

Is there is a way to add sounds for engine and radio to an add-on vehicle that doesn't have sound. Thanks.

@Reacon Yes it is cracked