I may not be hot on engines but I like my cars to look the part.
A large boulder got in the way of my wifes reversing and resulted in a new nearside rear bumper and all the other bits in 2003. The end cap was £36.91+ value? added tax from a Diahatsu main dealer and was obtained no problem with all the other bits including a specially imported Diahatsu chrome bumper which cost quite a bit but I saved my no claims bonus as I managed to fit them myself.
Re the existing end caps. Ive tried allsorts in tins but a decent product came from Wilkinsons in a trigger spray. Its like a black oil I simply unscrew the top, firmly hold a rag on top, tip up, then wipe on, let dry, and tickle with a duster to buff. It looks great on the other rubber bits too. You dont need to use much. Though the trims do fade again over time. Ive had it that long the labels unreadable.
By accident I discovered some original colour under the fade on my old damaged end trim when taking it off. I decided to experiment and got lot of colour back by rubbing the surface with fine wire wool, adding warm water and washing up liquid for stubborn bits but you have to let it dry to best see results. I even used the edge of a very sharp blade very lightly running it over the very stubborn bits at an angle. With any abrasion there is a fine line between taking the surface off and leaving scratches especially with the blade. I'd suggest trying a plastic blade like that in a tin of filler though it may take a bit longer. Whatever you use start off as lightly as you can and see how it goes gently increasing pressure if needed. I rub small areas in the same direction eg up and down or side to side. Ive done the same to my 3 old bumper trims in situ with good results. IF YOU TRY THIS I'D TEST A SMALL INCONSPICUOUS SPOT FIRST TO MAKE SURE YOU LIKE THE RESULT AND DONT RUIN YOURS!. I am just saying what I did to mine, you obviously do it at your own choice and risk. It took patience but once done looks better than before and when wiped over with the oily stuff will do for me and last longer than using the oily stuff alone. They do eventually begin to fade again but you can keep on top of them to keep them looking nearer black than all faded out. They now blend and dont look out of place with my new one, which will do for me.
Another tip my Sportys met black over silver. Ive used allsorts in a bucket but find Carplan Triple Wax to be pretty darn good followed by Carplan or Turtle colour restore wax. To me a better finish than some of the so called enthusiasts waxes I've used. Mines an old J reg and when a P reg pulled up at the side his jaw dropped, he couldnt take his eyes of mine all shiny and bright. Ok i'd spent the afternoon before on her. Ive used the above products for years and had some nice comments, the latest my daughters faded solid red banger. She cant believe the transformation. I find doing em regular helps keep them that way.