By Alan Baldwin

MEXICO CITY (Reuters) - Audi's announcement that it is abandoning Le Mans for Formula E is a big boost for the fledgling electric series, which is attracting growing manufacturer interest, and a blow for endurance racing.

Organizers of the Le Mans 24 Hours, the world's greatest sportscar race dating back to the 1920s, will take the news in their stride more easily than the world endurance series (WEC), however.

The French race is the crown jewel in the FIA-sanctioned WEC but stands apart as a highlight of the motorsport calendar, with tens of thousands of Britons traveling to France for their annual petrolhead festival.

"The race has been going for a long, long time and manufacturers have come and gone and been back again," Graeme Lowdon, whose Manor Motorsport team competes in the LMP2 category, told Reuters.

"The race is a lot stronger than any single component. I'm pretty sure there will still be 200-300,000 people turning up to see what is without any question one of the greatest challenges in motor racing.

"The manufacturers came and went in the 1990s and the event itself just went from strength to strength."

Audi notched up 13 Le Mans victories in 18 years and while their absence will be felt next season, they do not depart as champions.

Porsche, stablemates within the Volkswagen Group, have won the last two Le Mans and will continue to battle against Toyota. Ford, Ferrari, Aston Martin and Chevrolet also compete for GT class honors.

The impact on the FIA-sanctioned WEC will be greater, since two manufacturers in the top category is the bare minimum and Audi were stalwarts of the global series, but chief executive Gerard Neveu put a brave face on it.

"The WEC is made up of a grid of 32 cars, 20 teams, with four categories and six manufacturers entered," he said in a statement.

"One manufacturer is leaving, others will soon be arriving. This is the life of a championship."

Audi's shift in focus comes at a time when other manufacturers are looking with increasing interest at electric racing, and when a diesel emissions scandal is costing parent company Volkswagen billions.

A source at Audi said the move would save the company nearly 100 million euros per year.

The cost of running a Formula E team is a fraction of that involved in endurance racing, whose works outfits can spend as much as some top level Formula One entrants without the television revenues to offset the cost.

"From a VW group standpoint, they've got Porsche there," India's former F1 driver and Le Mans racer Karun Chandhok told Reuters ahead of Sunday's Mexican Formula One Grand Prix. "I know they target very different audiences and customers, but as a group they still won the last two Le Mans.

"You can see why they wouldn't want two competing brands spending a lot of money."

While Audi have raced diesel hybrids at Le Mans, Pierre Fillon, president of the Automobile Club de L'Ouest that runs the 24 Hours disputed the argument that the technology battleground was now elsewhere.

"Hybrid technology and electric motors are already part of our daily lives in endurance racing," he said.

"The changes to the technical regulations towards hydrogen-electric power responds straight away to the energy requirements of this new era."

The Green GT H2 this year became the first car powered by hydrogen fuel cells to lap at Le Mans in a demonstration run, with prototypes set to race in future.

Audi were involved in Formula E anyway with the ABT team and said the world's first all-electric series was a perfect fit for its aim to offer fully battery-electric cars from 2018.

"It is regarded as the racing series with the greatest potential for the future," the company said in a statement.

German rivals BMW and Mercedes have both expressed interest in Formula E while Renault, Jaguar, Citroen and India's Mahindra are already involved with teams.

"It is confirmation that Formula E is going in the right direction," Formula E Chief Executive Alejandro Agag told Reuters.

(Reporting by Alan Baldwin, editing by Pritha Sarkar)