By William Boston

BERLIN -- Volkswagen AG, the world's biggest car maker by sales, said Friday that net income more than doubled last year on the back of strong sales of its major marques and the effect of cost-cutting at its flagship VW brand.

The preliminary report lacked detail, but it suggested that earnings in the final three months of the year significantly missed analysts' targets. And Volkswagen's unambitious outlook for this year caused some analysts to raise concerns about the company's commitment to cutting costs and boosting profits.

"We are not impressed," said Arndt Ellinghorst, auto analyst at London-based brokerage Evercore ISI.

The costs of resolving the 2015 diesel emissions-cheating scandal continue to weigh on the company's earnings, but Volkswagen expects strong profit margins and an increase in revenue of as much as 5% this year.

In a preliminary earnings statement published after a meeting of the supervisory board in Wolfsburg, Germany, Volkswagen said net income was EUR11.4 billion ($14.06 billion) last year, up from EUR5.14 billion the year before.

Revenue rose 6.2%, to EUR230.7 billion, as unit sales increased 4.3%, to 10.7 million vehicles.

Volkswagen said it would propose an increase in its dividend, to EUR3.90 ($4.81) on ordinary shares and EUR3.96 on preferred shares from EUR2 and EUR2.06, respectively.

Looking ahead to 2018, Chief Executive Matthias Müller sounded a note of caution as the company shoulders huge investments in new technology for electric vehicles and self-driving cars amid a slowing global economy and mixed automotive markets.

"We -- like the entire industry -- are facing major challenges and radical change," he said.

Volkswagen predicted it would achieve a return on operating revenue in a range of 6.5% to 7.5% in 2018, which some analysts said wasn't ambitious and could suggest the company is slowing down cost-cutting efforts.

The diesel scandal continues to be a drag on the company's financial resources. Frank Witter, the company's finance chief, said Volkswagen had to digest cash outflows of more than EUR10 billion "due to the diesel issue, primarily for vehicle recalls and legal risks."

Volkswagen took diesel-related charges against earnings of EUR3.2 billion last year, down from EUR7.5 billion the previous year.

In China, Volkswagen's biggest single market, the company now is facing increased competition and higher costs to meet tough emissions regulation. Volkswagen doesn't consolidate its China revenue and profit, but said pretax profit from its China joint ventures was EUR4.7 billion last year, "down slightly" from the year before.

The company didn't provide details on the earnings at its brands, which include Porsche, Audi, Skoda, Seat, Lamborghini and Bentley. A detailed earnings report will be published in March.

Write to William Boston at william.boston@wsj.com

(END) Dow Jones Newswires

February 23, 2018 12:20 ET (17:20 GMT)

Copyright (c) 2018 Dow Jones & Company, Inc.