Lotus F1 team stretched components' reliability limits in 2015

Renault's protracted takeover of Lotus resulted in a lack of development of the E23 over the second half of the campaign.

The team's owners opted against continued investment with the squad about to be sold, while Renault refused to plough money into something it had not yet bought.

Trackside director of operations Permane said as well as upgrades being halted, a number of parts were pushed with regard to endurance.

"I complained and made no secret of the fact we didn't update the car enough," he told Autosport.

"But with the very limited resources we had the design office still pushed and did whatever it could do, no matter how small.

"There was still resolve, drive and everything from the people behind the scenes to get new stuff to the track and to keep trying to keep the cars running.

"Maintaining them is not an easy thing on a very limited budget. Obviously, we certainly never took anything past any safety limits.

"But on reliability limits, we took parts a lot further than we would have ever done before.

"The reason we were able to do that is because we took some parts and specifically R&D tested them for longer than you would normally, let's say.

"And we learned a little bit from something like that."

Permane confirmed there was a lot of frustration over the course of the season, particularly as the team knew it had a good car but could not develop it.

"We clearly designed a nice car over the winter, with both in the top 10 in Melbourne [qualifying]," he added.

"I wouldn't say we went backwards after that because there were highs and lows. Montreal and Spa, of course, were very good races.

"But we saw Force India come from behind and overtake us, and all credit to them, they did a great job.

"They really improved their car through the year, where ours pretty much stayed where it was, unfortunately.

"That was frustrating; to know you had something good and in a normal year you could have maintained its competitiveness, or even improved it, which we just weren't able to do.

"There is no doubt we could have had a very good, strong fifth in the constructors' championship if we had developed as normal. I really believe that."