hybrid prob?

hi, i picked my new clio 1.6 hybrid. my first experience of a hybrid. so bear with me lol.when starting the car from cold, it seems to rev its head of. it would last for around 10mins, but after driving it a while, it does the same thing for the rest of the day. it can get really loud. as i said, new owner, havent a clue as to whether it meant to be like that. i really hope not lol tia