* Says underlying demand remained soft at start of year
* Q4 EPS 0.62 euros vs 0.77 euros expected by analysts
* Shares drop 5 pct, underperform sector (Recasts with net profit, adds comparison to consensus, company comment on weak start of year, shares price)
FRANKFURT, March 7 (Reuters) - Lanxess, the world's largest synthetic-rubber maker, reported disappointing net profit for the final quarter of 2012 and warned that underlying demand remained weak across most of its businesses so far this year.
Lanxess relies on the automotive industry for 40 percent of its business and warned in November that it expected to reach the lower end of its forecast range for 2012 core profit growth as the European car market nears a 20-year low.
Earnings per share (EPS) jumped to 0.62 euros ($0.81) in the three months through December from 0.06 euros a year earlier, the company said on Thursday, unexpectedly publishing key financial results ahead of schedule.
Analysts had on average expected fourth-quarter EPS of 0.77 euros, according to Thomson Reuters StarMine.
"Soft underlying demand in the second half of 2012 has continued into 2013 across most businesses, against the usual seasonal trend," Lanxess said in a statement on Thursday.
A spokesman declined to say why the company released earnings ahead of March 21, when it plans to publish full financial figures for 2012.
Shares in Lanxess slipped 5 percent to 63.49 euros by 1223 GMT, making it the worst performer in the European chemicals sector, which was 0.2 percent lower.
Consultancy LMC Automotive said on Wednesday it sees western European demand for passenger cars shrinking 4 percent this year, the fourth straight annual decline, with conditions remaining "desperately weak as a dismal economic backdrop continues to hamper sales".
Lanxess earnings before interest, taxes, depreciation and amortisation (EBITDA), excluding special items, rose 7 percent to 1.23 billion euros in 2012, it said on Thursday.
In the fourth quarter alone, they were up 37 percent 239 million euros thanks to cost cuts. A devaluation of inventories in the previous year was not repeated.
Lanxess said it expected demand to pick up over the course of the year and affirmed its medium-term earnings outlook for adjusted EBITDA of 1.4 billion euros in 2014 and 1.8 billion euros in 2018.
($1 = 0.7692 euros) (Additional reporting By Christiaan Hetzner, editing by Paul Casciato)