* New trucks boss has to gauge need for acquisitions -Osterloh
* Rouble slump cost 3-digit mln-eur amount in Russia -Osterloh
WOLFSBURG, Germany, Jan 29 (Reuters) - Volkswagen ought to be able to cut costs at its troubled passenger-car brand by "substantially more" than the 5 billion euros ($5.7 billion) planned by the carmaker's top management, VW's works council chief said.
"With a bit more discipline one would easily be able to generate more efficiencies," Bernd Osterloh, VW's top labour representative, told reporters on Thursday at the carmaker's base in Wolfsburg, Germany.
Across the multi-brand group, the potential for savings is even bigger, he said, without being more specific.
Europe's largest automaker last July announced plans to cut 5 billion euros of costs at its core division by 2017 to plug the profit gap with rivals such as Toyota.
Steps to boost savings include plans to rein in costly vehicle equipment and cease some unprofitable models.
Separately, Osterloh, who also sits on VW's 20-member supervisory board, said the group's new truck chief, Andreas Renschler, has to gauge the need for possible acquisitions as he works to integrate VW's different truck units including Germany's MAN SE and Swedish manufacturer Scania.
Renschler, a former Daimler executive who will take up his new role at VW on Feb. 1, "needs to get an idea of whether we want to make purchases and what we need," said Osterloh. "With western Europe and Brazil only, this will be no success story."
On Russia, Osterloh said VW last year lost a three-digit million-euro amount due to the plunge of the rouble which has been hammered by the slump in oil prices and Western sanctions imposed over Russia's involvement in Ukraine.
$1 = 0.8846 euros Reporting by Andreas Cremer; Editing by Jonathan Gould