What is the future for Kers?
The new Kers power-boost and energy recovery systems have already spiced Formula 1 up this year, but their future is very much up in the air.
The systems, which store energy that would have been wasted during braking and re-apply it while the car accelerates, have been championed by Max Mosley, president of F1's governing body, the FIA.
Mosley sees in them a way F1 can be relevant to the future direction of road-car technology as well as protecting itself against accusations of profligacy in a world in which fossil fuels are running out and CO2 emissions urgently need to be reined in.
The systems, similar to those that are becoming increasingly prevalent in road cars, give a power boost of about 80bhp for nearly seven seconds a lap - and the fact that some teams are using them and some are not has led to some great racing between Kers and non-Kers cars this year.
At the moment, teams are free to develop their own Kers systems - with the main restriction being the amount of energy that can be released in one lap.
The problem is that developing them is very expensive - some teams are said to have spent as much as £45m on Kers - at a time when the world is in the middle of the biggest global financial crisis for decades.
Even before this season started, there was a move to delay their introduction by a year. And now there are calls for them to be banned - with Renault team boss Flavio Briatore apparently leading the way
That looks unlikely to happen - partly because, as McLaren team boss Martin Whitmarsh puts it, after starting work on a technology that is "relevant and interesting", it would be a shame to abandon it. But also because of Mosley's powerful backing.
But there is certainly a lot of discussion about what should happen.
At the moment, F1 appears to be heading towards a standard Kers system for next year - where all the teams pay money into a pot and one company builds the device.
That will cut costs dramatically. The problem is that it removes one of the justifications for F1 doing it in the first place.
That was that the white-heat of the F1 development race would ensure the systems were developed and perfected far quicker than would be the case if they were only being manufactured to fit into road cars.
But if only one system is being developed, the chances of that happening are greatly reduced.
It seems, though, that with the financial crisis being what it is, F1 feels it has no choice.
"At the moment," Whitmarsh says, "we are in an arms race. The technologies being used in F1 are quite similar, but the rules allow for a great diversity of technologies.
"It's a question of timing. In this climate, can we continue to have an arms race? It's an interesting area to have an arms race. But it's got to be commercially viable as well as technically interesting. We have to be pragmatic."