It's a mistake. The present tense is used for future events. Especially about intentions in the near future like pago io (I''ll pay). But to save hearts better to stick with the present even though the result, as above, sounds unnatural.
I borrow you my car is not possible. borrow is a transitive verb and needs to be followed by a nominal expression (like a name). The phrase you my car is not a nominal expression so the sentence is grammatically wrong.