Vettel, who replaced Pole Robert Kubica at BMW Sauber in 2007, managed to qualify seventh and finish eighth, his single point for that feat making him F1's youngest points-scorer - a record he still holds.
"It's all gone so quickly," he said.
"One hundred is a big number - 100 grands prix sounds a lot: 100 starts, 100 times surviving the first corner. If I reflect on it, it doesn't feel so long ago that I broke into Formula One ...
"That shows me that time flies when you do something that you really like and enjoy, so let's focus on the second 100!"
Vettel knows with a 10-point lead he can secure the title with a victory this weekend and that is his clear goal.
He enters the race with two races - worth a maximum of 50 points for two wins available - remaining.
He has 255 points to Alonso's 245.
In spite of his extraordinary success in the past three seasons, there are many who still find it difficult to pour praise on Vettel. This week 1997 drivers' champion Canadian Jacques Villeneuve joined that list of critics.
But Villeneuve said he felt Vettel was almost invincible if he could lead a race from the front.
"I have no doubts - Fernando Alonso is the best, that's why I root for him," he told Autosprint magazine.
"Seb is super quick, but there is a difference with Fernando that emerges in case of an unfavourable situation.
"Alonso remains calm, cool and rational, while Vettel most times gets upset, angry, screams and flicks the middle finger. He reacts like a child."
- AAP
