From autosport.com :

BMW Motorsport Director Mario Theissen has attacked plans to introduce customer cars in Formula One - telling autosport.com this is a completely wrong direction for the sport to head. As the possibility of legal action over Super Aguri and Scuderia Toro Rosso's 2007 plans looks increasingly likely, Theissen thinks there are even bigger issues at stake for F1. He believes the freeing up of chassis sharing rules from 2008 onward will rob the sport of variety, and could result in just six teams producing cars for racing. "There is this discussion about 2007, but to me the general view is more important," he said when asked by autosport.com about the future of customer cars in the sport. "I don't think it is good to sell chassis to a second team. "The original idea was to help smaller teams to become competitive in F1, that is a good approach and certainly it would help them if they can buy a chassis and not need to employ 300 people to design and build it. "On the other hand, as soon as such a rule comes in, I think the attitude of the independent teams will change. "Today we have independent teams who want to be competitive, who see themselves as one of 12 teams on the grid who fight for their own success. "With the chassis sale, I think we will very soon have six plus six teams - or six programmes with four cars each. "And there will be so-called independent teams who offer their services to the big teams in order to get chassis for free. "One has to think about whether that is good for F1. I would prefer having 12 teams, two cars each, everyone fighting for their own destiny and success." Theissen believes that the spectacle of the sport will be decreased by having just six manufacturer teams producing all the cars - especially if one of those car makers puts all its resources behind just one driver. "This is a really serious issue," he warned. "I think it will change the face of F1. "My fear is that there will be independent teams in the future who are not independent. I think every manufacturer would certainly think about having a second team, but it would lead to a situation of one team controlling four cars - and maybe using three cars to support the top driver. "We have always said that we support the current situation of having manufacturer teams as well as independent teams fighting for wins. "It is a healthy plan, and having just four or five big players controlling the grid in our view would not be F1 any more."

Hmmm, I don't really know - maybe it would then be more depending on the drivers to win races than on technology ?

Of course it would be bad to lose the independent teams, but aren't we currently losing them anyway ? Theissen himself played a big role in losing the independent team Sauber by buying the team and converting it into a manufacturer team

Sure, but yyou don't want to see 6 Ferrari teams, 6 McLaren teams, 6 Honda teams, etc but just under other names like Super Aguri, Giga Aguri, Toro Rosso, Roter Stier, etc just to get more cars, right ?

They should try to make sure the door remains open for independent teams to enter