I drive 2 weeks old Astra 1.4 100PS only 500km on odo. After just a few days of driving i noticed strange noise like howl just on 3rd gear exactly at 2500rpm. If I keep that rpm and slightly press the accelerator I get that noise but it dissapears at maybe 2600rpm. That howl changes frequency something like worn bearing. Is that normal or should I go to dealer or maybe I am expecting to much from Astra?