Judder Problems on idle and steering wheel shake at 65-70+mph

[A3Dave25]

Hi there everybody, I'm new to owning my first audi, it's a audi a3 sportback 2009 1.6 101 Mpi. I bought her from a dealer about 3 months ago, Since I bought her there's been a judder on idle although I didn't actually realise this at the time, they've had the car back and haven't been able to fix the problem, they've changed coil pack, new engine mount as they found it snapped still no joys on that however. They said they checked the car on a something scope (I can't remember what it's called lol) but it was fine all the way through the rev range so they said it isn't injectors, Can an exhaust cause a judder problem? Its quite rusty to be honest and when I rev her she sounds kind of loud to me from the center box, I started her up the other morning and I heard a hissing noise, so I look under the car and saw fluid dripping onto the cat from just in front of the cat fluid liquid I'm not mechanic whatever it is lol fell onto it and steamed up, I've used carista and dealers and no fault code show on theirs or mine, if I think I can do it I'll give it ago, also there's a steering wheel shake when I do around about 65+ on bumpy Road surfaces, fine on smooth as far as I can tell maybe a slight wobble dealer has had wheels balanced and car tracked and I have also still not joy at all, I was told the wrong wheels are on my car they should be 225/45r18 and there in 240/45r18 I believe off top of my head, if anyone needs clarification please let me know car might I add feels fine under load but she's idling at 680rpm does that seem right if I have air con on aswell the judder seems to some what go away if that helps there is also a strong smell of fuel when I go to the back of the car after long journeys only outside the car by the wheel arch and above etc , thanks in advance people and really sorry for the essay just wanted to try and explain my symptoms as much as possible, also when I turn the engine off sometimes I notice the car doing a very loud click from the engine bay area I believe confused as to what that is 😂 thanks again 

[cliffcoggin]

Dave.

The engine judder could be caused by any number of things, but a rusty exhaust is not one of them. The judder must be bad if it cracked an engine mount, and may also be responsible for a cracked exhaust.

The steering wheel wobble is most likely the road wheels are still not balanced. Have you hit the kerb? Other causes are worn steering or suspension joints, or loose bearings but as they are all MOT failures I hope the dealer has checked them.

Fluid of any sort should not be leaking onto the exhaust.

A stink of petrol at the rear of the car suggests a faulty breather, a leak from the tank, or a poor seal at the filler cap.

All in all you have bought a dog. I suggest you return it and demand a refund.

[A3Dave25]

I've had the car since March and I got it at 83000 miles and it's now on 87500 don't know if I still can?