Audi and Toyota are encouraged by the first tests of their 2015 cars

Audi completed its maiden test with the latest car to carry the R18 e-tron quattro nomenclature at the Motorland Aragon circuit in Spain. The run was described as "encouraging" by the head of the LMP1 programme, Christopher Reinke.

He would not divulge further details of the multi-day session, which followed tests of last year's car running 2015 components.

Toyota was at Aragon last week for the second test with its updated TS040 HYBRID, which followed an initial run at Paul Ricard in January.

Toyota Motorsport GmbH technical director Pascal Vasselon explained that the new car has so far completed "some decent mileage" over the course of the two tests.

"We have made some gains and we are happy that everything is going well," he said.

"But so far we are racing against ourselves and maybe the competition has progressed."

Toyota invited three new drivers to take part in the test: Kamui Kobayashi, Jean-Eric Vergne and Mathias Beche.

Vasselon said that they had been invited to take part because the team was undertaking a two-car test and needed additional driver. World champions Anthony Davidson and Sebastien Buemi and their 2015 team-mate Kazuki Nakajima were unable to attend because they had to be in Japan for the official announcement of Toyota's motorsport programmes.

"Three of our drivers were already booked, so we needed drivers to do a job," he explained.

"It wasn't a test to try three drivers, it was a test to put mileage on two cars."

He insisted that it was not a shoot-out for the position of test and reserve driver, but conceded that one of the trio would be given that role for 2015.

Nicolas Lapierre, who was dropped from the Toyota race line-up ahead of last October's Fuji WEC round, remains under contract, but will not have a role with the team.

Audi and Toyota have yet to reveal the technical specifications of their 2015 WEC contenders.

Audi has made no secret of its intention to move up a division from the two megajoule hybrid class.

Details of the new R18 are likely to be released later this month.

Toyota is trying to move from 6 to 8MJ and won't unveil its car until the day before the official WEC test at Ricard at the end of March.

It revealed last year that it could switch from a super-capacitor to a battery energy-storage system, but is known to have opted to stick with the technology it has used since 2012.