The Israel Antitrust Authority also found that gas stations belonging to small companies offered significantly lower prices.
The new carriages will operate on the Tel Aviv - Jerusalem fast link and other electrified lines.
The company is waiting for approval for a pipeline to take gas to Cyprus from the Karish and Tanin gas reservoirs.
A consortium headed by Bank Hapoalim is financing the project.
The company's share price surged 15% today.
ACU Strategic Partners wants to build nuclear reactors in Arab countries and make Israel responsible for guarding them.