U ovom kontekstu "trim" su oni elementi na spoljašnjosti automobila koji pored svoje osnovne funkcije imaju i ukrasnu funkciju (npr. razne lajsne za zaptivanje, obrub, zaštitu ili sa funkcijom odbojnika) i nazivaju se ukrasima, ukrasnim elementima. Mogu biti od različitih materijala - gume, plastike ili metala. "Black trim" bi bili crni ukrasni elementi / ukrasni elementi crne boje.
ukras - trim, escutcheon
npr.:
ukrasna presvlaka na stubu karoserije - pillar trim
ukrasni (završni) deo izduvne cevi - bright exhaust trim, ... exhaust trim
ref. Enciklopedijski rečnik motora i motornih vozila, A. Jovanović

Evo šta se sve podrazumeva pod "trim":
http://www.autopia.org/forum/guide-detailing/80228-detailing...
Common trim items include chrome bumpers, window molding, chrome light rings, chrome door handles, rubber door and bumper guards, window wipers, emblems and antennas. On classic and antique cars, you might also have horns, leather straps, hood ornaments and exposed exhaust manifolds.

http://www.mazda-rs.com/Modeli/MazdaMX5/Ukratko/tabid/5849/D...
Bez obzira na to odaberete li bezvremenski model s mekim platnenim krovom ili pak praktični „Roadster Coupé», raspon opcija snage i raznovrsnost boja karoserije, ukrasnih elemenata i dodatne opreme vrlo su široki.

http://www.ac-paveskovic.hr/
Od praktičnih i funkcionalnih rješenja za prtljagu, do ukrasnih elemenata koji naglašavaju dinamičnost vozila.

"Black trim wax" bi po meni bio "vosak za poliranje ukrasnih elemenata crne boje / crnih ukrasnih elemenata (mada je pitanje samo "black trim"). :)

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Note added at 14 hrs (2010-05-20 05:54:26 GMT)
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Evo komentara za Black Trim Wax:
http://www.reviewcentre.com/reviews142835.html
All-in-all this product is excellent. I have a Land Rover Freelander and the trims where looking very bland and grey, so I decided to buy this product from my local Halfords store. I decided to go one better with this product and made sure I had a full day to get the proffesional results I wanted. You will need to tape of the effected area, newsapapers and masking tape is a good idea. I then made sure the trim was clean and dry (all ways a good point). I then painted the liquid on to the trims. I left it for about 2 hours and then I painted another coat on (again leaving it for about 2 hours. After that I used an inexpensive electric hand buffer (for around £8.50) and polished off the trims (this took a few hours to do). The results were outstanding and most people thought I had fitted new trims. A bit of hard work but it was definitely worth it!
Ovde možete da vidite kako izgleda prethodno spomenuti Land Rover Freelander:
http://www.nextcar.com.au/i.landrover.freelander.se.green.ns...
"Black trim" su svi crni delovi na spoljašnjosti ovog vozila.


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Note added at 15 hrs (2010-05-20 06:41:03 GMT)
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Mislim da može, mada mi se čini da se "ukrasni elementi" češće koristi:
http://www.google.com/search?q="ukrasni elementi" automobil&...