Mother's Back to Black
 

works great for all the black pieces under the hood. Try it you will like it!

Anyone tried it on the bottom section of the rear bumper?

Yup.. I use that on the bottoms of my bumpers.. Not bad.. I like the deep black shine they give. Not oogie oily looking like Armor All.

Doesnt seem to last long though, I clean and reapply weekly. But that could be because of all the rain I've been driving through.

try mixing a bit of Interior Protectant with the Back to black for added protection.

Yeah, I used to use it on my wife's old '89 Civic hatchback. The bumpers and door trim would look great until the first or second day of rain, and then they'd be back to dull gray again. :(