Team boss Christian Horner has this week been quoted elsewhere as saying the RB10's performance was not a shock in Melbourne despite a disastrous winter season.
But Vettel, who saw his new teammate Daniel Ricciardo qualify and then finish second prior to his disqualification, has admitted he was surprised in Melbourne.
"The result was no great surprise -- what was a surprise was to see that the car is fast and we can compete at the front. The potential is there," the German told Bild am Sonntag newspaper.
"So it gives us hope and that's why I'm in a good mood," added Vettel.
After his four consecutive world championship successes, Bild reporter Nicola Pohl suggested to Vettel that he must be travelling to Malaysia feeling frustrated.
But he insisted: "I am in good spirits! I knew that this year would be difficult, but each season has its ups and downs.
"As for the car, there is still much to learn but there is no reason to hang the head."