BARCELONA, Spain - Jenson Button shifted uneasily on Sunday when, after finishing eighth for McLaren in the Spanish Grand Prix, he was asked if the performance of his car was improving.After four races without a podium finish, he and the team had hoped for some improvement but, as he conceded, it did not really happen.The 2009 World champion said: "Well, I don't know, I don't think so really. For me it was an interesting race."LOTS TO DO"My start wasn't very strong which was unusual because we are usually strong at the start. Turn one was a mess so to finish eighth probably wasn't too bad but there is a lot of work still to do," said Button."Some of the speeds cars were going past me means we have a lot to do.""It is still possible for us to get up there and I want to thank all the fans for their support, it's a bit embarrassing really to see them all, but we will get it right," he added.After five races former World champion Button is languishing in 10th place in the drivers standings with just 17 points. Stay with Wheels24 for the 2013 Formula 1 season – fresh reports every day.