My wife has a '71 Beetle that she uses 2 or 3 days a week for local journeys.

It live outside and I'd like to get a cover for it to help protect it a bit (and so I can run a dehumidifier/battery conditioner in it when it's not in use).

Criteria are;

1) Waterproof!
2) Can be put on a wet car.
3) Can be put on/taken off easily – we don't want 20 minutes faffing before she goes to work of a morning.

Any suggestions?

I've used covers on my car before and they're only really suitable for putting on a clean dry car. This was with a 400 quid breathable cover too.

The time you spend faffing with a cover several times a week would be better spent washing it once a week in my opinion. The battery conditioner could be kept dry under the bonnet etc.