"Compared to last year, we have made a huge step back in every area it looks like at the moment, " said Button, who was third in the championship in 2004.

BBC: SPORT | Motorsport | Formula One | Button fires angry salvo at BAR

Design-wise, as we said, it looks like the S7, particularly with the lid shut, and it's now made from one piece of aluminum, instead of several.

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