Sutton pipped Dan Cammish, his stablemate in the line-up of NAPA-liveried Motorbase Ford Focuses, by 0.015 seconds with a time set during the morning of the second day of running on Wednesday.
Twelve of the top 13 set their best times across the two days during this session, and Sutton was one of those trialling a new soft-compound Goodyear as the BTCC gears up for the return of option tyres in 2023.
Sutton acknowledged that the rubber was key to his beating the time of Cammish, who showed consistent form to finish in the top six in each session.
“We were selected to do some Goodyear tyre testing,” said Sutton. “So pretty much our whole day was based around testing out the option tyre and a few other things.
“I kind of took the limelight away from Dan who had raw pace on the right tyre if I'm honest. We were just running a completely different programme, as requested by Goodyear.
“We still made good progress with the car over the two days. We feel like we've had a lot of potential and that potential seemed to be showing in Dan's pace too.”
Tandy, who previously tested for Motorbase in 2013 and was fresh from class victory in the Monza 6 Hours World Endurance Championship round with Corvette, joined the team in a spare NAPA Focus, which he shared on the first day with Motorbase’s Mini Challenge protege Jack Mitchell.
He then split driving duties in team regular Sam Osborne’s car on the second day. “Working with Nick [Tandy] has been absolutely mega,” said the son of team principal Pete Osborne. “He’s a fantastic driver and has given lots of great feedback which I can take forward.”
Jake Hill finished up third overall in the test in the best of the West Surrey Racing-run BMW 330e M Sports, the Kentishman in the top five in all four sessions, including setting the top time on the final afternoon.
He edged out championship leader Tom Ingram, who was in the top four in all sessions at the wheel of his Excelr8 Motorsport Hyundai i30 N.
Gordon Shedden was quickest in both sessions on the opening day in his Team Dynamics Honda Civic Type R, but dropped to fifth on the second morning when the top times were set, ahead of Ricky Collard’s Speedworks Motorsport Toyota Corolla and the Power Maxed Racing Vauxhall Astra of Michael Crees.
Shedden’s team-mate Dan Rowbottom was the only driver in the top 13 not to set his best time on Wednesday morning, his afternoon effort giving him second place in that session and eighth overall.
Jason Plato (BTC Racing Honda) and Stephen Jelley (WSR BMW) rounded out the top 10.
Current points runner-up Josh Cook languished in 17th place in his BTC Honda, and missed the second morning due to technical problems.
The same went for double Croft winner Dan Lloyd, who also had to skip the opening day with the Excelr8 Hyundai squad for budget reasons, but went sixth on the final afternoon.
Excelr8 also ran its Mini Challenge ace Dan Zelos in the car normally raced by Jack Butel.
BTC, meanwhile, was down to two Hondas with Jade Edwards absent from the driving seat at the test, although she was present at Snetterton.
