The Renault-Nissan automaking alliance emerged as the world's biggest seller of light vehicles in 2017, bumping Volkswagen AG off the top spot, after the inclusion of Mitsubishi Motors' numbers boosted its final tally.

Nissan Motor Co's sales hit a record high of 5.82 million, while French automaker Renault SA has reported sales of 3.76 million. Mitsubishi's sales came in at 1.03 million, bringing total 2017 sales for the group to around 10.61 million light vehicles. Together, the three automakers beat record sales of around 10.53 million light vehicles at Volkswagen, 2016's top seller, which also includes the Audi, Skoda, Seat and Porsche brands.

Toyota Motor Corp, which held the No. 2 spot in 2016, posted group sales of 10.2 million units last year, excluding its Hino Motors heavy trucks. Many automakers are trying to boost sales volumes to achieve economies of scale and cut costs amid soaring investments needed to develop next-generation automotive technologies - including self-driving cars, electric vehicles and new mobility services.

This has been a focus of the Renault-Nissan group, and was a key motivation for Nissan when it acquired a controlling stake in smaller rival Mitsubishi Motors in 2016. Renault-Nissan Chairman Carlos Ghosn has pledged to make scale an advantage and use it to double savings to 10 billion euros ($12 billion) by 2022, based on a rise in annual sales volumes to 14 million units.

Renault, Nissan and some other automakers are looking to share more vehicle parts and consolidate production platforms to trim R&D and manufacturing costs and raise profitability. Toyota is taking a similar approach, while it is also partnering Mazda Motor Corp and Suzuki Motor Corp to reign in the costs of developing and marketing electric cars and other new technologies.

But not all automakers consider scale as a way to increased efficiency and profitability. General Motors Co has concluded that size does not matter as much, selling its struggling European operation Opel to PSA last year to focus capital on more profitable ventures.

The strategy seems to have worked for the US automaker, which posted a profit margin of 6.8 per cent in January-September. That was higher than a 5 per cent margin at Nissan and 4.3 per cent at Mitsubishi Motors in the six months through October, and a 4.8 per cent margin at Renault over January-June.

Earlier this month, GM pointed to new trucks and SUVs, a new, low-cost car for international markets, and the Cadillac luxury brand as possible future earnings drivers.

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