this is a relative answer, as it was ridiculous bad considering my expectations, before anyone jumps on me and says it's far from a bad car:
53 plate Merc E320 CDI elegance estate.
where to start? Such an awful car! Absolutely awful engine and gearbox (auto), it got worse economy than my 330i sport despite driving it easier, it REALLY didn't like corners i think the steering wheel was put there for ornamental purposes only, the seats were awful and unsupportive and the ride wasnt even that great, it was that wafty that after a bump it took too long to settle back down.
Worst bit is? Apparantly thats how mercs are meant to feel, but imo it wasnt even relaxing, i felt sea sick on anything but the smoothest, straightest road. Ill reserve judgement against all mercs until ive driven a known good example as this couldve been a nail i suppose. It had only coverd 55k miles though :\
Surely better than a Vauxhall Cavalier, though?