Fitted my S3 Sigma with or without the spare wheel attached. No long needed as I traded the S3 in on a new toy.
I have used this outside occasionally and it seemed to keep the car quite dry even in a downpour. But you would need a half hood on too if there was any serious rain, to stop it pooling above the driver’s seat.
Bad points (see pictures) - Its got a little wear at the front as it's been rubbing against the number plate and a tiny hole near the back of the car where I caught it on something sharp in the shed, but I think both of these are simple repairs and didn't seem to effect the waterproofness.
£30 seems reasonable? I'm between Reading and Oxford postcode RG8 for pickup or can pop it in the post if you pay PnP.