HI all i'm looking for some advice. I bought a mazda 2 2017 last week and on the drive home i noticed there is a strange vibrating/warbling sound on pulling away. I didn't notice it on the test drive and it is very subtle but it's starting to do my head in. I've messaged the dealer who said if it's driving well which it is let it develop and he will take care of it but it doesn't seem right. It only happens when pulling away from a standing start in first or reverse but reverse is possibly a bit worse. I can feel it a bit through the pedal, sometimes it's more noticeable than others. If i put the brake on and try to pull away it doesn't happen.

Ive added a video but i'm not sure a phone mic picks it up well although it's clearer with headphones. Any help would be appreciated. Thanks in advance