Sebastian Vettel said he will not publicly compare Aston Martin's Mercedes engine to Ferrari's out of respect to his former team.
Vettel joined Aston Martin for its return F1 project this year, after his six-year stint with Ferrari came to an end. It is his first time driving a Mercedes power unit -- the German manufacturer has won every championship since the introduction of V6 turbo engines in 2014.
Vettel has been driving his new car at preseason testing in Bahrain.
When asked to compare the Mercedes to Ferrari, he said: "It's obviously different but I'm not going to compare, just out of respect to different manufacturers.