Finally, someone who is willing to put forth a well thought out argument for "hiding a car's true performance".
All teams generally run the car for fastest times with next to no fuel in at the last test once they have gathered all the data for the long run/tyre wear etc as seen by this weeks testing. It has been the case for years.
I would dispute this. My belief is that all teams will run their cars are varying fuel loads and setups. At some point they will run with a super heavy car. And at some point they will run their car with an ultra light fuel load. I'm not sure that the light fuel load is always done at the final test.
None of the top teams like to reveal their outright pace straight away as it shows exactly where their car is at. With no fuel in the car, with the car set up for fast laps, it is very easy for the rivals to calculate the true speed. The longer they can cover it up the more it keeps the others guessing.
What advantage would the other teams get if they realise that the McLaren, say, is 1s/lap faster than they are? There isnt anything they can do about it, unless you are suggesting that rival teams are holding back on purpose and if they see the McLaren going 1s/lap faster than their own car, they will suddenly release a "secret" part which they were originally holding back (on purpose), so that they don't get beaten so badly.
At all times, teams are looking to make their car go as fast as possible and working their hardest to make this happen. Seeing a McLaren go 1s/lap faster than a Ferrari say, will not make Ferrari suddenly go faster or work harder.
For the above reason, my belief is that it doesnt make any difference if McLaren (or any other team), shows their true pace. In fact, it is in the best interest of any given team, to carry out their tests/laps, without attempting to hide their performance, as it is quite possibe that this strategy will hinder their own development.
This has always been the case & is exactly why when new bits are added to the cars the top teams try & cover them up as long as possible. It's all about preserving your advantages.
This is the only paragraph I agree with, for the following reason.
When new pieces are added, teams will do their best to hide them from the other teams. The reason for this is that if other teams see a team like McLaren, say, using this new part, and it gives McLaren a 1s/lap advantage, then the other teams will investigate this new part and begin developing it, themselves. We saw this last year with the double diffuser. It is therefore in the interests of McLaren (or any other team), to hide the "secret" parts from their competitors.