16:26 Aug 18, 2009 

Indeed ajovaloumpio is traditionally "headlamp insert" in English, as in this classic German car: http://www.ldm-tuning.de/en/artikel-55.htm
However modern vehicles do not have such inserts and the wider concept is referred to as "ajovaloumpio" (not valokaluste as in MOT). Also these kind of lamp inserts do not curve in the way described in the question "pitkät lokasuojiin kaartuvat valoumpiot"
The vehicle in question seems to be Citroen C3 Picasso http://umami.fi/vapaa-aika/tiia/autokuume-nousee-2/ and thus the correct translation would be "light / lamp assembly" rather than light insert.

15:15 Aug 18, 2009 

Other terms used to translate valoumpio are lamp cluster, lamp unit.
See automotive link http://www.motorera.com/dictionary/LA.HTM
Terminology varies because of wide variety of terms used to describe the same thing, depending on the location of the English speaker.

14:48 Aug 18, 2009 

is "valokaluste" acccording to the MOT dictionary. It's a wider concept than "valoumpio".
http://www.cisionwire.fi/veho-group-/uusi-e-sarja-saa-euroop...
and in Englih:
http://www.emercedesbenz.com/May09/22_001659_BRABUS_Tunes_Th...
They use "carbon fiber inserts" (hiilikuituvalot eli hiilarit) in the link.

As for the link provided by Desmond, it's most interesting, but not very convincing in this case. I could not find any evidence there. I'd trust, for example, the websites provided by Mercedes Benz and the like. They know the terms they use are accurate and up-to-date.

If it's C3 Picasso, the answer is here:
http://www.newspress.co.uk/DAILY_LINKS/arc_apr_2009/57355cit...
They are simply "headlamps" (at the beginning it says "incisive, high-set headlamps").