Volkswagen will become the world’s biggest carmaker this year – a full seven years earlier than its management’s aim to replace Toyota in the industry’s top spot, according to three leading consultancies.

Forecasts show that VW’s relentless growth around the world, coupled with Toyota’s supply-chain problems after this year’s earthquake in Japan, mean the German automaker will claim the number one spot for both sales and production.

The result, if borne out by year-end tallies, would mark an upset in an intensely competitive industry where Toyota and General Motors have for the past several years vied for the title of biggest.

It would also cap a remarkable turnround for the German group, which only five years ago was largely written off due to some of the highest labour costs in the industry and internal management strife.

In 2008 when Martin Winterkorn, VW’s chief executive, vowed to overtake Toyota by 2018, few took it seriously as VW sold about three million fewer cars than its Japanese rival.

But since then VW has exploited its position as the top-selling carmaker in China, the world’s biggest car market, and has even managed to increase sales by eight per cent this year in a stagnating European market.

It has also become one of the industry’s most skilful practitioners of platform sharing across its brands. That has allowed it to trump rivals on cost by virtue of its economies of scale.

So far VW has escaped the managerial overstretch that tripped up both GM and Toyota after their ascent to the top, although it has suffered setbacks recently in its bid to merge with Porsche and form a viable alliance with Suzuki, its estranged Japanese partner.

VW sold a record four million vehicles in the first half of this year and Mr Winterkorn says group sales could reach eight million by the year-end.

Nigel Griffiths, chief automotive economist with IHS Automotive, said: “They are doing a really good job with their core product lines. They have strong tailwinds from all the work they’ve done in China, and are making progress in the US, where they have been underperforming for so long.”

JD Power, the consultancy, estimates that by year-end VW will have sold 7.8m vehicles, with 10.5 per cent global market share; GM will be second, with sales of 7.2m followed by Renault and Nissan with combined sales of 6.8 milion, and Toyota fourth, with 6.7million.

Both IHS Automotive and PwC Autofacts forecast that VW will be on top, followed by GM, which it expects to pip Toyota.

PwC Autofacts, meanwhile, estimates that VW will be the car industry’s largest producer this year, followed by GM and Toyota. Vehicle sales roughly mirror production in an industry where most producers keep tight inventories.

JD Power’s forecasts include actual sales through August, and projections for the balance of the year.

Mr Schuster cautioned that VW’s place in the league tables could still shift, but said he still expected it to retain its number one position at the year end.