form populated with data from dropdown

Hello

I dont know where to post this question so i post here.

In my site theres form where logged user can add his car details (model, engine etc) and part which he needs along with adress. I get data from form in my email and send that part to him. It must be simple no ecommerce, because user do not buy products.

Many users have few cars.

I want to make form where user can add car or few cars. And then display dropdown where user can choose one of his cars. This data populate form except car part field which user fills and hits send button.

I was looking for plugin which helps me do this, but cant find anything.