After receiving your advice I was left speechless for some while. I cannot express how thankful I am to you for sharing your insight.
As you had noticed, I was leaning a bit towards the [fast rising startup] decision and needed a confirmation I am heading in the right direction. I have to admit I was just scared that whatever I decide, I will regret missing the other opportunity. However, you not only gave me this encouragement, but you also contributed with remarks about issues I was not aware of, or because of being emotionally involved in the decision, I could not notice.
Now, it all makes much more sense to me and the decision became somewhat easier: before I had a feeling like choosing either option meant some sacrifices, but your argumentation shows me, that working at [top tier automotive brand] does not close the door for a [fast rising startup] career in the future. Therefore, my decision will be to work for [top tier automotive brand].
Yet again, thank you for your great help and giving me the confidence I needed.