Mothers detailing clay or Clay magic.
they both make quick work of ANY contaminants i've EVER had on my cars. i use it on the entire car from time to time. makes it feel like a PANE OF GLASS and eliminates that slight "gritty" feeling that you can never seem to remove with a regular washing. especially on the front bumpers and behind the wheels (i removed my mud gaurds). i highly recommend this to all of you. it looks nicer than a detail shop does. here's the steps i do (when its nice out)
1-wash car completely & rinse
2-mothers detailing clay
3-rinse & towel dry
4-meguiars cleanser (pt 1 of 3 step deep crystal system

nice also)
5-megiars polish (pt 2)
6-meguiars solid carnuba wax (pt 3)
the car couldn't look better from any detail shop! and occasionally (twice a year) i use a buffer.