Gulf financing

Servus, I have a question and that’s what I have to get a Golf 7. However, not as a cash purchase but financing. At the moment I earn 350€ a month & the car would cost 250, the VW Bank gives me alone with this naturally without a guarantor not this credit. Now the question: How much would my income have to be that I can finance the amount of 250€ without a guarantor? there is something like a table or decide the times so? Of course I get from my parents still money for fuel and from time to time also what of grandparents etc for insurance but as guarantor they do not want to be registered. Another question would still be if I could get the credit only on me from 600€ monthly income then I could also work also where other work e.g. for 250€ so that I get total to 600€ or does not go with 2 different salaries or do I have to tax the money then or not ? Thank you