what’s the difference between say “i have a car” and "i’ve got a car " ? both sentences are in simple present ?
“I’ve got…” = “I have got…” <— This is the present perfect.
The two examples you gave mean the same thing.
Eu “tenho” um carro e Eu “comprei” um carro. 
Saudes.
My Two cents,
While both “I’ve got and I have got” mean the same thing there is a distinction between the two.
“I’ve got” is more informal. “I have got” is more “proper” . In other words, if you were speaking with a professor (or the Queen) you would use “I have got”. With friends you could use either “I’ve got” or “I have got”.
By the way in the word ‘I’ve’ the apostrope replaces the letters h & a (from the word have).
Michael
I agree with Imyirtsehem. As a Canadian, I too, would simply say “I’ve got a car” in everyday speech but I couldn’t envision myself saying “I have a car”- it sounds strange to me.
Well, I’ve got to go read Le Hobbit
M
I do not recall ever hearing anyone say ‘I have got,’ this is always shortened to ‘I’ve got.’
‘I have gotten,’ is a fairly common expression, as a casual replacement for ‘received.’ Very very often this will be shortened to ‘I’ve gotten.’
‘I have a car’ does not sound strange to me at all, although ‘I’ve got a car’ is probably what is said most often.
‘I own a car’ is formal, potentially to the point of being pompous.
‘Got’ is an informal word, ‘have’ is not. The grammar police would say you should say ‘have’ all of the time. But there are situations where ‘got’ sounds much more natural. If someone asks you if you have your car keys, you stop, check for them in your pocket, and you respond 'Got ‘em!’
If you think about it, ‘I’ve got’ is like saying ‘I have have,’ it’s superfluous. Technically, ‘I got’ should be more correct, but it definitely isn’t!
Nice explanation lapoubelle. I do want to disagree with the last sentence. In ‘I have got a car’, the have is not superfluous because in this context, ‘have’ does not have the same meaning as it does in the phrase ‘I have a car’. In 'I have got a car, the ‘have’ is the auxiliary verb in a present perfect construction, and is not the verb ‘to have’.
[EDIT]: But of course what you say about ‘got’ being superfluous is true since it can be left out and the meaning of the sentence is not changed.
I’ve almost never explained my complete beginners that ‘I have’ Present Simple is, and ‘I’ve got’ - Present Perfect.
I do it, but later.
I just tell them: you can say - I have a car= I have got a car’= I’ve got a car, adding that "I’ve got a car’ is the most colloquial.
It’s sufficient, and it works.
Probably it is better to do it that way for beginners. For German, I thought it was very useful, but that is probably because I was going from English to German and so it was very easy to understand by analogy.
“Got” is slang. When I was at school (in England) we were not allowed to use the word. Any homework we wrote that included the word “got” would have been returned with a warning written in red that we should not use this word. Having said that, it is certainly very popular slang, and perhaps my teachers were being too formal.
I don’t think they were being too formal. ‘Got’ is a word that should probably be avoided in any kind of formal writing; it really jumps off the page in a negative way.
It would be quite shocking to come across ‘got’ in a non-opinion based newspaper article for example. Even in a magazine you wouldn’t find it, unless the writer also used a lot of other slang to go with it.
I would also say that if you use ‘got’ in a cover letter when applying for a job, your chances of landing the position will decrease greatly. (unless you’re attempting a very casual writing style)