> Do you know how those car electronics product use multicore? 

ENOIDEA

NEC MP211 product can be seen in NECele WWW site and the following
articles might be worth reading (both in JP).
 
http://k-tai.impress.co.jp/cda/article/news_toppage/20699.html
http://www.labs.nec.co.jp/Overview/soshiki/device/0503.pdf

There is Linux port for it and NECele has obligation to disclose the src.

Toru Nishimura/ALKYL Technology