Purely anecdotal, but I got back into cycling this year, partly as I missed it, partly for fitness, partly because I work nearer to home and can cycle to work some days, and yes, save some ££ on petrol. As it happens I bought s/h, so I'm not part of the statistics! But it's good to hear that it is a general increase in all bike sales.
Two of my mates have since started cycling to work and one has bought a new bike (after seeing my single speed).
As for bad weather cycling, sorry but on shitty winter days I'm taking the car! (no showers at work either so its a practical thing as much as anything).