For the first time this year, Lotus Renault GP experimented with a rear-facing exhaust on its R31 during opening practice for the German Grand Prix at the N?rburgring - although the lack of any long runs for either driver has left the team on the back foot somewhat heading into Saturday.

Lotus Renault GP featured a unique, front-exiting exhaust system during the opening nine races of the F1 2011 campaign - initially, to great effect - but is evaluating the potential switch to a more conventional rear-exiting system from this weekend onwards.

Home hero Nick Heidfeld was entrusted with putting the new exhaust through its paces at the N?rburgring - along with a complementary prototype rear floor, made of metal parts and four kilograms heavier than a full carbon fibre alternative - and he lapped just 15th fastest on Friday morning but a more encouraging eighth-quickest in the afternoon. According to the BBC, however, the experienced German has opted to revert to the forward-exiting design from FP3 onwards.

"These were two important sessions for us, as we were able to try the new exhaust and diffuser," the 34-year-old acknowledged. "We had no technical issues, which enabled us to work through a lot of our planned programme, so we can now make a decision of where to go next with it. As I was evaluating the new parts, I did a lot less balance work than I would have done otherwise. We also didn't do a high-fuel long run, which we would normally [do] as we focussed on learning as much as we could with the new exhaust and floor.

"Even though it's quite cool, the soft Pirellis are heating up pretty well, so there were no problems in that regard and there was the usual difference between the two compounds. There's now a lot of work to see what we do with the floor and what happens with the weather. It was good that it was dry, but the forecast doesn't look as good for the next two days..."

Team-mate Vitaly Petrov, for his part, joined in with the testing of the raft of revisions for the struggling R31 brought to Germany, trying out a new front floor and front wing but suffering a water leak in the afternoon session that necessitated a radiator change. The young Russian concluded proceedings a smidgen slower than Heidfeld in ninth place.

"We did a lot of aero testing and worked on a number of set-ups," revealed the 26-year-old. "It was my first time on this circuit, so I needed some time to get to know it and to understand how to drive here. Set-up wise, we are not far away from a good car, even after our running was interrupted by a radiator leak which cost us a little bit of time in second practice. The soft tyres had more grip than we experienced with them previously. All-in-all, we were pleased with progress."

"Due to Vitaly's water leak and Nick's exhaust evaluation, we did not run a high-fuel long run," rued LRGP chief race engineer Alan Permane at the end of a typically chilly and cloudy day in the Eifel Mountains. "We are on a steep learning curve with the rearward-facing exhaust, but we made strong progress through the two sessions. There were no issues with balance, and we have a good baseline set-up here with both car configurations. We have a lot of data to digest for determining which exhaust configuration we will use for qualifying and the race."

Those sentiments were echoed by the Enstone-based outfit's technical director James Allison, who had vowed to 'let the car do the talking in the coming races' [see interview here] with regard to forthcoming updates and modifications.

"We had a reasonable day," he affirmed. "What I meant by letting the cars do the talking is that we have got a number of improvements to bring over the next several races that we hope will restore us to something closer to where we were at the start of the year than we have been in the last two or three races. It is very easy to talk about 'you've got this and you've got that', but it will be much nicer when we have actually put it on the track and everyone can see it - so hopefully that's what will happen."

One factor that should help in that respect is Lotus Renault GP's recent upgrade of its wind tunnel from a 50 per cent scale to 60 per cent. It was, Allison concedes, quite an upheaval.

"Well, it is a lot of work, that's for sure," he confessed. "People call wind-tunnel models 'models', but they are not really models at all. They are things that cost almost as much as making a real car and are almost as complicated.

"Just changing the model from 50 per cent to 60 per cent is already a large engineering exercise, but in our case as well, the wind tunnel working section wasn't really quite big enough to support a 60 per cent model, so we needed to strip that back to its bare skeleton and replace it with something that was man enough for a 60 per cent model.

"All-told, it was a project that started around about a year ago and culminated just recently, [but] very little actual wind tunnel time [was lost], as one of the most precious things to all teams is to keep that tunnel running and to keep the aero development going, so we made sure we could do the swap-over with the minimum amount of disruption to the actual tunnel testing. We had the tunnel down for twelve days."

Allison spoke, finally, of being appointed as the new head of the Formula One Teams' Association (FOTA) Technical Regulations Working Group. If it is an honour, it is also, he concedes, 'a significant responsibility'.

"I think everyone would agree that FOTA is a group that has acted strongly and very constructively in the interests of the sport," the Englishman reflected, "and the technical regulations working group is one part of what FOTA does. It's a part which tries to look constructively in the medium and long-term to contribute to making the rules of the sport work well, working hand-in-hand with the FIA to do that, and hopefully I can pick up [from] where some of my predecessors have left off in looking after those meetings in an efficient way."