Most teams have a blown diffuser, so this isn’t about making the gap smaller. In fact it could hurt Renault as much as Red Bull, not a good thing if they want closer competition.
The “mode” which will be banned is also atypical. Most of the time F1 cars are on the throttle, not off it. Sure, it’s the part which gains lap time, but it’s only a small part of the overall downforce.
Also, even though I’m no fan of this halfway-house of green technology in F1, it’s pretty stupid to have an engine manufacturer admit that it’s burning fuel up just to power an aerodynamic device. Bear in mind the FIA have a long-standing agenda of limiting cornering speeds and cutting costs – big amounts have already been spent trying to catch up to Renault and even more would be needed to eliminate the gap. The DDD put a giant hole into the FIA’s plans on this front. They couldn’t ban it because it wasn’t against the rules. They couldn’t ban it for the next year (2010) because it would reduce the 2009 arms race to nothing. Finally getting rid of it for 2011, nothing happens. So from their point of view, they had to do something.
So let’s not be jumping to any conclusions just yet, please? In an added bonus, throttle-only feeding of the exhaust requires a specific driving skill to maximise it, to be a bit more daring with the throttle. Ironically given comments so far, this may tilt the balance of F1 a tiny bit in favour of sport and skill rather than machinery, which no-one can say is under-represented in F1 today.