'07 C200 acceleration

[alpha channel]

After acquiring an '07 C200 CDI for a bit of economy driving and having had it for a good few months now I'd just like to know what these things are supposed to accelerate like. At this moment in time when I pull away it's as if the car is acting a bit on the petulant side, i.e. I stick my foot down to accelerate onto a roundabout (from a standstill) only to find that damn thing crawls away, then after a couple of seconds thinking about it it takes off like a bat out of hell (usually because I've got the go pedal pinned to the floor and swearing at it to get a move on). The only time I can get a reasonably rapid acceleration is if I 'load' the throttle and dump the clutch.

Is this normal for these things? (I hope not, it has admittedly been a while since I've had an oil burner, better part of a decade, even then they were an '86 205 and a '91 Clio).