Caterham has followed Williams’ lead by removing a dubious solution for its Coanda-effect exhaust from its 2013 car.
Williams tweaked the specification of its FW35 as last week’s testing concluded, and on Thursday - as the final days of running in Barcelona began - it was clear Caterham was also now fielding a more conventional design.
In the green car, Frenchman Charles Pic ended Thursday’s running a half-second behind the Marussia.
In Speed Week, technical expert Gary Anderson said the black and red Lotus is offering drivers Kimi Raikkonen and Romain Grosjean "outstanding" traction.
"In that respect," he said, "the Caterham is the opposite of a Lotus."