When i did my engine bay -
I used a small amount of de-greaser on any oily and grimey bits and wiped off sraight after.
Plastic - vinyl cleaner and dressing on hoses etc
Any paintwork cleaned and waxed.
The first clean takes a while, but once clean it doesn't take a few minutes each week to wipe clean etc
I'm afraid it's just a case of elbow grease mate
the pics dont do it any justice, you should see it in the flesh! looks brand new out the factory, immaculate isnt the word for it, even the heatshield on the mani looks brand new!!
me, i go for the 'driven' look, i have a vented bonnet, let the wind clean it as it rushes through! :wink: