|By Andrew Benson, Chief F1 writer|
Susie Wolff admits she feels "very far away" from becoming the first woman to race in Formula 1 for 40 years.
The Scot will drive for Williams at the Spanish Grand Prix first practice on Friday but realises she may never race.
"I have shown I am capable, I'm in a very competitive team, I drive a car which is capable of podium positions," Wolff said.
But she admitted that Williams's decision to sign Adrian Sutil as their reserve driver this season was a blow.
"That was a sign that, 'Yes, you're close, but you are still very far away'," she said.
|Female drivers in F1|
|Maria Teresa de Filippis - 5 races (1958-69), 3 starts - 0 points|
|Lella Lombardi - 17 races (1974-76), 12 starts - 0.5 points|
|Divina Galica - 3 races (1976 & 78), 0 starts (did not qualify)|
|Desire Wilson - 1 race (1980), 0 starts (did not qualify)|
|Giovanna Amati - 3 races (1992), 0 starts (did not qualify)|
Williams went into the season without an official reserve driver, with Wolff designated as test driver and British GP2 driver Alex Lynn their development driver.
But when race driver Valtteri Bottas suffered a back injury and was forced to miss the season-opening grand prix in Australia, the team had no one able to stand in at short notice.
Wolff only has a licence to drive in practice, not races, and the team felt that it would be too big a risk to ask her to drive in a grand prix when her last single-seater race was a decade ago in Formula Three.
Wolff, now 32, has not raced at all since 2012, when she completed the last of seven years in the DTM German touring car championship.
And a new point-based qualifying system for super-licences to be introduced next year will make it all the harder for those who have not won junior or qualifying championships.
"To find the budget to go through all those formulas, to get into the right team so that you actually win the championship in those formulas, that is a huge task for any driver regardless of gender," Wolff added.
"I hope it will get tweaked and adjusted.
"Love it or hate it, motorsport is not purely talent. It never has been and never will be."