The madcap conclusion to the Chinese Grand Prix, with 12 cars battling nose to tail for second place behind winner Nico Rosberg, was packed with some of the best racing Formula 1 could ever produce.

But among the wheel-to-wheel battles and overtaking moves, one incident stood out more than most.

With 20 laps to go, Mark Webber's Red Bull ran a little wide on the 170mph exit of Turn 13, caught the edge of the kerb, and its nose reared up into the air.

The car looked briefly as if it might take off - as Webber did in the 2010 European Grand Prix, when his car landed upside down before skidding into the barriers, without injury to its driver. He also suffered two similar accidents at Le Mans in 1999.

But then the nose crashed down on to the track. "It's always a worrying moment when it gets a lot of air under it like that," said team boss Christian Horner. "He's used to that. I should think he was on the brakes."

He wasn't, as it turns out. Webber told me a "little lift" of the accelerator was enough to bring the car back down again.

For those watching, it was a heart-stopping moment. But Webber obviously did not dwell on it long - in the very next sector of the lap, he set his fastest time of the race so far.

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Shanghai was another impressive weekend from Webber, notwithstanding a couple of errors that probably cost him a podium finish.

He spent last year in the shadow of team-mate Sebastian Vettel as the German cantered to a second world title. While Vettel took 11 victories, Webber won once in Brazil - and then only when Vettel's car hit gearbox trouble.

This year is a different story. Not only have Red Bull slipped back into the pack, but Webber has so far had the edge on Vettel.

The qualifying score is three-nil in Webber's favour and the final overtaking move in those frantic concluding laps in China was Webber separating his team-mate from fourth place between the penultimate and final corners of the last lap.

It was the climactic moment of a fascinating weekend at Red Bull, whose drivers were in cars of two different specifications.

Vettel has never been happy with the handling of the RB8 in the upgraded trim that was introduced at the final pre-season test. And for China he reverted to the specification in which the car was launched, while Webber stuck with the newer one.

According to chief technical officer Adrian Newey, incidentally, the car was in exactly its initial configuration - not, as we reported over the weekend, with slightly longer exhaust pipes.

The two designs have a different aerodynamic philosophy.

The older one uses the exhausts to improve the airflow through the "coke-bottle" area at the rear of the car. The newer one aims to direct the gases at the area where the floor meets the rear tyre, to "seal" the diffuser.

Both improve downforce, but to different degrees, in different ways and with different effects.

"There were some characteristics about the upgraded car that weren't particularly suited to (Vettel's) style of driving, which is to carry a lot of speed into the corner," said Horner.

Vettel qualified only 11th, but said afterwards that he "felt happier with the car than (in) previous races". But the decision to put him back into the older-spec car in China was not, Newey said in an exclusive interview after the race, at the driver's request.

The newer car had shown "a few characteristics that haven't worked as intended," Newey explained, "so we simply brought the old bodywork for Seb this weekend to get some more data, as a direct comparison."

It was a test session, basically, and Vettel was chosen to run the older-spec car because he preferred its handling.

"We could have then put both cars to the latest spec, the spec that Mark raced, on Friday evening," Newey said. "But we felt that would be more disruptive than simply continuing. And we'd have probably burnt a (mandatory FIA working hours) curfew in the process. But both cars will be back to the new spec in Bahrain."

Newey clearly believes the newer car is faster, but he says it's "difficult to say" by how much.

I pressed him, asking if he thought the difference in performance between the two cars was in the region of the 0.331 seconds by which Webber was faster than Vettel in second qualifying, which Vettel did not progress beyond.

Newey said: "Mark seems to have taken to this car more easily than Seb at the moment, but that's simply the reverse of what happened last year."

Indeed it is. But why?

Engineers in rivals teams say Red Bull have been hurt more than any other team by the banning of exhaust-blown diffusers this year because they were exploiting the technology, which pumped exhaust gases along the floor of the car even when the driver was off the throttle, far more effectively than anyone else.

Red Bull pioneered it. If you got it right, and combined it effectively with the overall design of the car, it could gain you something in the region of a second a lap. But it was difficult to master the aerodynamic effects and most teams never did.

This year, the teams are still trying to exploit exhausts gases in a similar way, to hold on to some of the downforce-boosting effect. But the regulations now define an area within which the exhaust exits must be, engine mapping is restricted, and the gains are reduced to about 10% of what was available in 2011.

Webber never really got on with the way the Red Bull behaved last year.

But this year the cars are handling in a more conventional fashion, and he is back to where he was in 2010, when he and Vettel were evenly matched and Webber led the championship for much of the year.

The Red Bull drivers' Chinese GP results match their championship positions. Webber is fourth on 36 points, eight ahead of Vettel and nine behind leader Lewis Hamilton.

Whether Red Bull can improve their car enough to fight consistently for victories - and therefore the title - remains to be seen. But they are too good a team, led by too brilliant a designer, to stay down for long.

And the battle between their drivers adds a delicious extra dimension to their fightback.

