I understand your frustration, I really do! I'm a hobbyist detailer, but I'm pretty enthusiastic about it, and I look after all the families cars etc... The hardest one to maintain and keep it looking good is my Mother-In-Laws white Range Rover Evoque. It looks stonking when it's clean but terrible when dirty!

It was a nightmare UNTIL... I properly cleansed it using tar/iron remover/clay etc and applied a ceramic sealant on it last Jan. Now, all it needs is a quick wash and its back at its best.
These sealants do resist dirt to some degree, so it would stay cleaner for a little longer.
I'd highly recommend having one applied to make the maintenance much easier for yourself. Give me a shout if you want any help, further assistance, I'd even offer to do it for you (if you're in Cheshire you're not too far from me!)
Although I've ordered Tornado Red, white is a stunning colour and looks the business IMO.