Ford factory drivers Jari-Matti Latvala and Petter Solberg say the M-Sport team has made a big step forward with the Fiesta RS WRC after dominating day one of Rally GB.
The Fords were fastest on all six stages through mid-Wales on Friday, leaving Latvala and Solberg first and second as the cars arrived back in Cardiff.
"We have worked hard on the rear suspension in the last test," said leader Latvala. "We don't have anything new, but the team has just been looking at the front-rear balance of the car. It's fantastic now.
"Since winning Rally Sweden earlier this year, I haven't had such a good day as today - I have real confidence in this car and we have to thank the team for this."
Solberg added that the car's balance was significantly improved.
"The car feels calmer," he said. "It holds the line and doesn't oversteer. It's just fantastic."