You might, but if you are your friend's manager instead of just his friend then you should take the opportunity to get better at asking for feedback to do a better job of managing the relationship.

Because what a manager should take away from that is that they weren't prepared enough - they could have asked "what do you think the most important aspects of buying a car are?" first and if "color" was the answer then either not asked for feedback or asked for feedback on something that would lead to a decision being made. The question was too vague.

If you ask someone for their opinion, learn they don't like blue cars, then ignore it and buy a blue car ... you could do more to be respectful there. You don't need to do special work to respect your friend - presumably the relationship is strong and they can just walk out if they don't think the respect balance is good. But really things are better if a manager respects their reports.