Rubens Barrichello has admitted that it is difficult to say exactly what the real reason is for Honda's failure to perform this year.

Honda has had an abysmal season and thus far has only scored two world championship points.

Rubens himself has yet to get off the mark and when asked prior to this weekend's Japanese Grand Prix what has gone wrong, the Brazilian noted that while the RA107 is better than the 2006 model, the main problem is that they didn't move on as much as their rivals.

"It's very difficult to know what the real reason is [for our lack of form]," he explained. "The car is not worse than last year's car - basically everyone else improved, and we didn't.

"The car last year was fine, and they took a different route for this year to improve something that was OK already. They didn't pay attention to the aerodynamics and fine-tuning of the car.

"To go right to the bottom and understand why that happened, I didn't bother, because right now I'm focused on trying to help the new guys understand and make it better.

"I never thought that the 2006 car was a great, great car - it was doing OK on the Michelin tyres and we had a good package at some of the races, but it wasn't there to win every race. I had problems to adapt to it, especially to the traction control.

"This year everything is much better on that side - although the car is miles away - so it's about putting everything together with the new guys there to make it work. It seems already that next year's car is coming along better."

As for the Japanese Grand Prix itself, Rubens noted that if they can scrap into the points at Fuji Speedway they will be doing well.

"It's the home race for Honda and we definitely want to do very well. But apart from that, we know that the car isn't very good - and the year hasn't gone very well," he continued.

"We just have to put the best effort to try and compensate for that, but if it is anything, it's a single point more than anything else - unless the weather can play a different part and then you never know."