Lexus paint is very soft and although Black is one of the
best colours when clean and new it is the worst colour to keep looking that way, it shows every chip, scratch and swirl mark. So you really need to protect it as much as you can from new, I had a complete new car protection treatment done on my car, ( see link below ) this adds a very hard protective layer on top of the lacquer already on the car but is much harder, this reduces the chances of light scratches and swirl marks, you just then have to make sure you clean the car using the right products and in the right way.
Snow foam, two bucket system, soft mit ( not a sponge ), micro fibre clothes, ( not a chamois ), Aqua Gleam de-ionising water filter.
All this costs money, so it all depends on how far you
really want to go.
http://www.theultimatefinish.co.uk/car-care-blog/new-car-protection/lexus-rc-f-born-on-fuji-speedway-protected-at-brands-hatch/