For 2012 and 2013 Williams will have Renault Engines the BBC reports.
Williams think that Cosworth have shown they are not committed to making winning engines it seems.
It's been almost 20 years since Cosworth engines were really successful in F1 and that was Schumacher in Benetton.
I don't know why Williams decided to use Cosworth for the last two years.
I would have thought, maybe, just maybe, 11 years of sub-par Williams performance with 5 different engines would finally at some point make people realise that its not the engine that has been the main problem at this team. Apparently not.
There was nothing wrong with the Cosworth mechanically. Its weight, power, reliability and fuel consumption appear to be just as good as everyone elses (in fact there were rumours its one of the more powerful engines available). The only issue with Cosworth lately has been engine electronics and generally engine maps. But this is down to Cosworth being missing for 3 years in F1, money and time will eventually solve this issue.
The problem is a mixture of things:
1. Money, Williams simply don't have the budget to compete with the top teams these days.
2. Aerodynamics, they've really never replaced Adrian Newey properly and many believe that Williams stronger years 2000-2004 were more down to BMW power and that those cars were not the best they could be aero-design wise.
3. Strategy/Management, even when Williams have had a great car at some race weekends, they have bungled their strategies and made mistakes which have cost them potential wins, podiums and points.
I don't see Renault changing anything for Williams. What will change their fortunes is the major changes behind the scenes with Coughlan moving in and according to rumour - Colin Kolles. Sam Michael isn't the reason Williams have faded either though, he is a capable engineer/manager.
Its kind of sad for Cosworth (and Toyota and BMW) that when and if Williams do return to form, people will cite the Renault engine as the reason, when it couldn't be further from the truth.
If anyone wants direct proof that engines don't make a huge difference these days, look no further than the Lotus T127 and T128. Even with much more time and money spent on aerodynamics and two different engines, Lotus are still pretty much where they have always been (which is an achievement in itself in F1). The switch from Cosworth to Renault hasn't really made a huge difference for Lotus, which clearly demonstrates that aerodynamics are the bigger factor these days. It will be no different for Williams.