Sebastian Vettel has vowed no let-up in the final four races of the season, starting with this weekend's 2012 Indian F1 GP as he bids to become the youngest three-times World champion.The 25-year-old Red Bull driver won the previous three races to set up his third successive title and could have considered easing off and taking a pragmatic percentage approach to the title run-in.CLOSING INBut the German, who now leads nearest rival double World champion Fernando Alonso of Ferrari by six points, said he would not be changing his aggressive approach. "It's a better position to be in compared to the position we had three or four races ago. We'll try to do our best in the next couple of races to make sure that we stay there, but in terms of our approach nothing really changes."They will be extremely important races for us. We have to try to do our best and then go from there."The double World champion said being the hunted, instead of the hunter, was not something that worried him."We are in a good position but we are not in a position to sit back. That's why I remain focused and we will push as hard as we can to make sure that we stay where we are."Stay with Wheels24 for the 2012 Indian F1 GP weekend.