PARIS, July 8 (Reuters) - Fading Formula One champions Renault expect to show their true colours from next month's Turkish Grand Prix, according to team president Alain Dassas.

He told Reuters on Sunday that they aimed to have a car ready for Istanbul, the 12th race of the year on August 26, that would be "not the final version but a chassis we should have had at the start of the season."

Finnish rookie Heikki Kovalainen and Italian Giancarlo Fisichella finished seventh and eighth respectively in Sunday's British Grand Prix, leaving the team fourth in the constructors' championship with 31 points.

The team, who declared in May that their minimum target was to finish the season in third place, are 25 points behind nearest rivals BMW Sauber and 97 adrift of leaders McLaren after nine races.

Sunday's race marked Renault's 30th anniversary in Formula One and, in an interview at the carmaker's flagship showroom on the Champs Elysees in central Paris, Dassas said the team were still fighting hard.

He said a decision on who would be the drivers next year remained open.

"Kovalainen has not yet been able to fully prove himself because we do not have a good chassis but from Turkey he should be able to prove his worth," he said.

The team also have Brazilian test driver Nelson Piquet junior, son of the former triple champion, lobbying hard for a race seat.

Renault have been champions for the last two seasons but have not appeared on the podium yet this season following the departure of tyre partners Michelin.