If you don't know the response then "This car look familiar to you?" is correct. If the person you are asking stated that the car looks familiar and you are asking because you want to clarify then "This car looks familiar to you?" is correct. Both are correct but the meanings are different. "I don’t suppose you could upload a list of those locations to my PDA, could you?" sounds like you are politely asking for a favor. "I suppose you couldn't upload a list of those locations to my PDA, could you?" Sounds like you are saying the person tried to upload the list but for some reason they couldn't.

I would say that if we go with looks ... you think the vehicle is familiar and expect the person to say yes. If we say look ... we are genuinely asking a question and have no idea of the answer. And, the first sentence is better. The second is also grammatically correct but the first is far more natural and practical.

I will just mention that both your first examples sound very American to me. British English speakers are much less likely to drop the 'does'. I agree with John's interpretation of the difference. In your second example, your first version is very polite, and correct. As Amani said, your revision completely inverts the logic: it changes from a request to upload, to a query to confirm an inability to do so.

Interesting question because both ways work but mean something different. "This vehicle look familiar to you" implies question where the questioner is just looking for information that he does not yet know. "This vehicle looks familiar to you" implies that person who saw the vehicle has already said it looks familiar, and the questioner is surprised and is asking the person to reconfirm. Example 1: Two people find a lost purse at school. There is a good reason to think that one of the persons might know whose purse it is. One says to the other "This purse look familiar to you?" Example 2: Two people find a lost purse in the middle of a forest. There is no reason to think either person would know whose purse it is. But one person unexpectly says: "I recognize that purse." The second person says, with surprise, "This purse looks familiar to you?" About your PDA question, the first way is correct.