So the teams are discussing a return to testing in season (albeit without an increase initially in total number of days) with a test possibly at Mugello before the European season begins. Testing was curtailed in 2009 because of the huge expense of having a race team and test team. However with 21 races on the Calendar next year we could see teams having to adopt 2 teams of personel anyway, but according to Sam Michael the real cost was engine mileage. Teams were using an extreme amount of engines (which are now limited to 8 per season per driver/car, plus i believe one for testing) before this regulation teams were using 30/40/50 engines per driver a season!
However I think the most logical thing would be to allow teams to run a driver different to their race drivers and provide them an extra engine per season and a set of each compound per race. Therefore due to the limited running that is done in practice session due to the limits on tires could be alievated. This would force teams to run an extra driver to gain the use of extra tires and if time got too tight in the session extend FP1 to 2 hours.
While the test engine would be the main cost, the teams would not have to bring another car and it would be done at the race track. I think this is the best option for running more drivers in F1 cars and increase running for those attending on Friday. It would also be an incentive for fans to attend Friday sessions as you would get to see additional drivers (and I would imagine teams running national drivers in some GP’s – IE running someone like Danika Patrick in Friday practice next year in the states would be immense).
The rules might have to be tweaked to allow the teams to hold onto their tires for longer (say FP2 for regular drivers) as they have to hand back a certain amount of tires at the end of Free Practice sessions to force the teams to run and not save tires.