The three-time champion started his Motorbase Performance Ford Focus ST from second on the grid, but he was on the soft Goodyear tyre whereas pole-sitting team-mate Dan Cammish was on the medium compound.
Predictably, the extra grip helped Sutton get in front at the start, and he continued to pull away, setting the fastest lap along the way, to win by 7.682 seconds.
Cammish himself was untroubled, while Dan Rowbottom, also on the medium tyres, completed the second 1-2-3 of the day for the NAPA-liveried Fords.
Sutton paid tribute to set-up tweaks made on Saturday night at the behest of his engineer Antonio Carrozza, which he had resisted when Carrozza suggested them in qualifying.
“Those changes overnight have definitely worked and the car came alive on the soft tyre,” said Sutton.
“All cars come alive on the soft tyre, but that was something else.
“I got a nice launch on the soft, but I had to go late on the brakes into the first corner to make it stick on Dan.”
While it was serene for the leading pair, Rowbottom was fighting a lairy-looking car and had reigning champion Tom Ingram breathing down his neck in his Excelr8 Motorsport Hyundai i30 N.
Ingram, from sixth on the grid, had jumped ahead of Josh Cook and Jake Hill on the opening lap to move up to fourth.
For the first third of the race, Rowbottom appeared to be holding up a train comprising Ingram, Cook (One Motorsport Honda Civic Type R), plus the West Surrey Racing-run BMW 330e M Sports of Hill, Colin Turkington and Stephen Jelley.
Ingram did jump ahead when he got down the inside of Rowbottom at the hairpin at the end of the fourth lap, but the Ford was on the inside for the following Clervaux and regained third spot.
By half-distance, Rowbottom and Ingram had edged away from the pack, and now Cook, who was on soft tyres, appeared to be the cork in the bottle – Hill, Turkington, Jelley and now Ricky Collard were queued up behind.
Hill got ultra-close to Cook at the beginning of the 10th lap of 15 but got two wheels into the gravel on the exit of Clervaux and spun down to 11th at Hawthorns.
Cook thereafter kept his eye on Turkington, and by parking the Honda on the apex of the hairpin on the final lap he made sure of fifth spot.
Turkington’s sixth position gave him the reversed-grid pole for the final race, while Jelley was seventh ahead of Collard’s Speedworks Motorsport Toyota Corolla and the Team Hard Cupra Leon of Dan Lloyd, who had latched onto this group by the finish.
Tom Chilton took the final spot in the top 10 in his Excelr8 Hyundai.
BTCC Croft - Race 2 results (15 laps)
| Cla | Driver | Car / Engine | Time | Gap |
| 1 | Ash Sutton | Ford | 20m50.890s | |
| 2 | Dan Cammish | Ford | 20m58.572s | 7.682s |
| 3 | Dan Rowbottom | Ford | 21m00.743s | 9.853s |
| 4 | Tom Ingram | Hyundai | 21m01.497s | 10.607s |
| 5 | Josh Cook | Honda | 21m04.497s | 13.607s |
| 6 | Colin Turkington | BMW | 21m04.863s | 13.973s |
| 7 | Stephen Jelley | BMW | 21m05.182s | 14.292s |
| 8 | Ricky Collard | Toyota | 21m05.993s | 15.103s |
| 9 | Dan Lloyd | Cupra/TOCA | 21m06.517s | 15.627s |
| 10 | Tom Chilton | Hyundai | 21m08.012s | 17.122s |
| 11 | Jake Hill | BMW | 21m12.729s | 21.839s |
| 12 | Árón T.-Smith | Vauxhall/TOCA | 21m13.140s | 22.250s |
| 13 | Adam Morgan | BMW | 21m13.666s | 22.776s |
| 14 | Sam Osborne | Ford | 21m20.717s | 29.827s |
| 15 | Andrew Watson | Vauxhall/TOCA | 21m21.154s | 30.264s |
| 16 | Mikey Doble | Vauxhall/TOCA | 21m21.952s | 31.062s |
| 17 | Aiden Moffat | Honda | 21m22.331s | 31.441s |
| 18 | Rory Butcher | Toyota | 21m24.376s | 33.486s |
| 10-second penalty |
||||
| 19 | Michael Crees | Cupra/TOCA | 21m25.673s | 34.783s |
| 20 | Jack Butel | Cupra/TOCA | 21m27.236s | 36.346s |
| 21 | Daryl Taylor | Cupra/TOCA | 21m34.872s | 43.982s |
| 22 | Nick Halstead | Hyundai | 21m35.111s | 44.221s |
| 23 | Jade Edwards | Cupra/TOCA | 21m36.138s | 45.248s |
| 10-second penalty |
||||
| 24 | Ronan Pearson | Hyundai | 21m11.119s | 1 lap /20.229s |
| (24) | George Gamble | Toyota | Retirement | |
| (26) | Dexter Patterson | Cupra/TOCA | Retirement | |
