I'm thinking they sound a lot like the current generation of Indy Cars.

The regenerative motor between the exhaust turbine and the intake turbine is what you are hearing, instead of wasting the unused exhaust pressure it is used by generating electricity with said motor, This same motor is used for spool up of the turbod so they don't have any lag....
Awesome tech.....

Discount anything in that vid with a Renault engine, I think Red Bull never got their engine to make it past warm up laps without problems.

The lack of traction control, and the need to keep the car in one piece for what is primarily engine oriented tested as opposed to handling, means the driver's aren't pushing like it was a race. Massa and Alonso I think were trying to vie for top time of the day, so if you were to see some of the Footage from those laps - you'd get a better idea than watching the short shifting renault cars that make up quite a bit of that clip.

Edit, I because of the extensive regenerative systems, pushing the brakes to the limit into a corner would also be important to the tests.

You can see from this one segment with the Ferrari how much the car's are leaving on the table in that vid.
http://youtu.be/s99QFe6htJ4?t=2m18s

Quote from Rosberg - "When I was in the car on day two, the mileage was good, but boy, it was a fight in the cockpit. The tyres wouldn't come up to temperature and we were going so slow - like GP2 times - so we have to adjust to all that. Only work will get you there."

Sounds like it will be a thrilling year.

Less downforce, harder tires, cornering speeds are down... Quite a few of the drivers are complaining already.

http://forums.pelicanparts.com/uploa...1391517354.jpg