Nick Chester discusses the 2015 Lotus
In an interview published on the Lotus F1 team's website, Nick Chester - Technical Director - discussed the work currently being done by the Enstone team in preparation for the next season.

For Nick Chester, the transition from the 2014 single-seater, the E22, to the 2015 model, the E23, does not result in a significant modification of the various concepts as the regulations are generally stable for the next season. The real change occurred at the beginning of the year.
The preparations for the E22 were significant – there were so many regulatory changes as well as the new power unit to consider. Everything was different. The E23 project is somewhat reduced thanks to more stable regulations, and even though we have a new power unit [Mercedes, Editor’s Note], the changes in architecture are a less significant challenge than the transition from the V8 to the V6 turbo, explains Chester on the Lotus website.
Even though there are no major changes for 2015, Lotus has been working for several months on the E23, which is well underway: We started working on the 2015 project in January of this year. […] Our first chassis is currently under construction, and we will gradually produce all the parts for the race. We will start building the E23 at the beginning of January.
The Enstone team had to take into account a new parameter in the design, the shift from the Renault engine block to that of Mercedes, but this is not problematic: « There are a number of differences to consider, such as heat rejection and cooling needs. At the same time, if we had continued with Renault Sport F1, there would also have been changes for 2015. My feeling is that this does not represent a significant amount of additional work. It’s more a matter of adaptation. »
The team’s drivers, Romain Grosjean and Pastor Maldonado, tested parts planned for the next season and their feedback is important for the engineers in order to best target the direction to go: « We have gathered all the drivers’ feedback on the current car and are making sure we fully understand where they feel the shortcomings are so we can rectify them for the new car. »
Nick Chester believes that the continuity of the driver duo is important because as the relationship between the drivers and the engineers develops, the engineers are better able to understand the wishes of their drivers: « Yes [it’s important to have continuity with the drivers], because you have a better understanding of the drivers’ feedback. »
It should be noted at this time that only Pastor Maldonado has been confirmed at Lotus for 2015, although the extension of Romain Grosjean seems to be on track. Announcements on the Frenchman’s Twitter feed and Facebook page were even made before being quickly deleted.