* Sees adj. EPS down 50 pct in 2013
* Shares fall 10 pct on outlook
* Q4 results lifted by one-off tax gain
By Sara Webb
AMSTERDAM, Feb 12 (Reuters) - TomTom, Europe's largest maker of navigation devices and among the three biggest digital map-makers in the world, said earnings would halve this year because of weak car sales and competition from providers of free maps.
The firm's share price plunged 10 percent on the warning, hitting the lowest level since the end of August, 2012.
TomTom is trying to increase sales of its navigation gadgets and services to car makers to offset the declining popularity of stand-alone personal sat-navs.
But its fortunes are closely tied to those of customers such as PSA Peugeot Citroen, Renault, and Fiat , which have been hit by weak consumer demand.
"It (2012) was a disastrous year" for European car makers, Chief Executive Harold Goddijn, told Reuters: "2013 won't be easy but I don't think it will be as bad".
France's mass-market car brands are suffering more than most from Europe's deep car sales slump, punished by their exposure to austerity-hit southern markets.
TomTom forecast earnings per share - adjusted for impairment, acquisition-related amortisation and restructuring charges - of about 0.20 euros in 2013, down 50 percent from the 2012 EPS of 0.40 euros and the lowest since its listing in 2005.
It also said 2013 revenue would be in the range of 900 million euros to 950 million euros, down from 1.06 billion euros in 2012.
"It's too early to say if and when we can go back to growth. We will have to include that in our forecast for 2014," Goddijn told reporters on a conference call.
The company has reported a drop in EPS in each of the past five years.
TomTom, which competes in the personal navigation device (PND) market with Garmin and in the commercial digital map market with Google and Nokia, said it expected its core PND markets to decline by 15-20 percent in volume year over year.
TomTom reported quarterly net profit of 99 million euros lifted by a tax gain of about 80 million euros, on revenue of 289 million euros.
Analysts polled by Reuters had on average forecast a fourth-quarter net profit of 7.95 million euros on sales of 284 million euros.