Apparently the answer is to do a ceramic coating then for the next 18 months a quick hose down and you have a sparkly bike.
This is according to the gurus on GCN.
I thought I would give this a go for my new bike as wanted to keep it pristine as long as possible, so bought the G techniq kit for about £45. Very expensive but it treated 4 bikes plus an extra set of wheels with it. And it does work - water just beads off so nowhere near as much dirt sticks to the bike. Very similar effect to car wax, but much easier to apply; it even leaves a nice shine and makes light scratches less visible. I haven't had it long enough to comment on durability, but it is still beading water off the surface well after a few washes (and you will still need to wash, it just saves a load of effort whilst you do).
What I can say is you don't need to spend £45 on the G techniq kit. It just contains an isopropyl alchohol spray to clean upfront, an applicator pad, a couple of microfibre cloths plus about 35ml of the actual ceramic coat fluid. You can get exactly the same stuff for cars in far bigger quantities off
eBay or Aliexpress for a fraction of the price - which I did, and got 2 * 50 ml replacement pots for about £8 (and IPA spray is cheap and well worth having for cleaning brakes and other things). Even if the coating only lasts a few months that still ends up a fairly cheap and low effort way of 'waxing' your bike. And of course now I have an unlimited cheap supply I can now ceramic coat my helmet, shades, shoes....