Team Lotus has confirmed that it will not use KERS at the start of the 2011 season, though it reckons it could add the energy recovery device at a later stage if necessary.
Chief designer Lewis Butler said his team had decided that KERS would have forced too many compromises in other areas of the design.
"The decision not to use KERS made the design job slightly easier, because packaging it in the car is always a bit more of a headache," he said.
Lotus' head of aerodynamics Marianne Hinson said the system would have forced particular compromises for her department.
"It's the same for us in aerodynamics: no KERS is actually easier because packaging all the bits you need for it is actually quite limiting for some of the aero shapes you need in some areas," she explained.
The team's chief operating officer, Keith Saunt, said Lotus felt the potential gains from having KERS did not outweigh the packaging disadvantages at this stage in the outfit's development.
"If KERS was going to get us from eighth to sixth then we'd have it," he said. "But when you look at the weight of it and some of the engineering challenges, I think it's a good decision not to start with it."
He joked that he was sure Lotus could cope if it had to add KERS to the design later in the season.
"We might end up with it, who knows?" said Saunt. "But if we did, we've got a lot of experienced people who could turn their hands to it.
"If we had to design a motorized catamaran canoe in a day, I reckon we could do that, too! We've got some very clever people here."
The T128 does feature the mandatory movable rear wing, the other main rule change for 2011, and sporting director Dieter Gass is confident Lotus has done well in this area.
"It was a bit less of a challenge than I thought it would be," he said. "Once you've looked at all the different concepts you can use, it wasn't that hard to achieve a solution. I think we have quite a neat, simple system on this car."