I will try to explain the differences. The correct sentence would be: If I really wanted that car, I would have to pay.... Why? wanted referrs to a hypothesis, as you do not really want the car, but you say, if I want it, then, and there is a condition bound to that. As for the second part, it refers to the wanted, therefore you take the same form, as they both are just assumptions. This has nothing to do with the past in this case. The sentence in the present would be: If I want this car, I will have to pay. Again both auxiliary verbs are in the same time, only present now. What is the difference? In the first example, you started your consideration of buying the car in the past. In the second example you are making plans for the present and ongoing future. And for the past, another example: If I had wanted this car, I would have had to pay... This way you are saying, that the process of decision has passed. You cannot make another choice now, it happened and is over. Always the verbs stand in the same time in each part of the sentence, at least in those cases. There are other examples where this rule does not apply, but in your case, it is always like this.. examples for:.would have paid - I would have paid you, if I had known you needed the money. If I had known means, that now it is over, and I cannot change it. I haven't known the important news, when they were relevant example for would pay: I would pay the price if I where you, it's very cheap. You should really pay it, in my opinion. The conditional here stands for an impossibility. I am not you, but in your situation you should do it. Hope the examples help you

Ok first, If I had wanted to buy this car, I would have paid around 1000 euro. (This is the 3rd conditional, Past and Unreal. You did not buy the car, so you did not pay 1000 euro. If I wanted to buy this car, I would pay around 1000 euro. (This is 2nd conditional, Present and also Unreal. You do not want to buy the car, so you will not pay 1000 euro. Neither one is future. The 3rd usually expresses regret over something you did and feel bad about, or didn`t do and should have done. 2nd expresses unreal situations now, that cannot or will not happen. Mixed time conditionals are more difficult, usually past events affecting the present: I would not be so tired now if I hadn`t stayed up so late yesterday. If I had studied harder, I wouldn`t be failing the class.