British Touring Car star Matt Neal and his Honda squad are pushing forward with developments to the Civic because they believe rivals will close the gap in 2013.
Honda swept all available BTCC titles with its new NGTC Civic last season, with Gordon Shedden and team-mate Neal finishing one-two in the drivers' standings.
Despite the strong campaign, in which the Civic took 14 wins, Neal believes improvements will be needed for this year.
"We've been working hard in all areas of the car during the break," Neal told AUTOSPORT. "We've not stood still over the winter.
"I expect the level of opposition to be a bit higher and for that reason we have to push to make sure we're still tough to beat."
Neal believes the 2012 performance of the Civic will help others push forward with their own cars.
"We were the first to understand the NGTC regulations and get on top of everything," he added. "Everyone has seen our car now and will have had the winter to improve."
Neal confirmed some of the improvements concerned "optimising the engine for the regulations".
The Civic spent most of 2012 on its low baseline turbo boost level.
2013 British Touring Car line-up so far:
Team Car Drivers
Honda (Team Dynamics) Honda Civic Gordon Shedden/Matt Neal
MG (Triple 8) MG6 Jason Plato/TBA
Motorbase Performance Ford Focus Mat Jackson/TBA
WSR BMW 1 Series C Turkington/R Collard/N Foster
Team HARD VW Passat Tom Onslow-Cole
Vauxhall Insignia Jack Goff/James Cole
Speedworks Motorsport Toyota Avensis Dave Newsham/TBA
Ciceley Racing Toyota Avensis Adam Morgan
IP Tech Race Chevrolet Cruze Andy Neate
AmD Tuning VW Golf/Vauxhall Astra TBA
Rob Austin Racing Audi A4 Rob Austin/Will Bratt
Eurotech Racing Honda Civic Andrew Jordan/TBA
Dynojet Toyota Avensis Frank Wrathall