Cook started his BTC Racing Honda Civic Type R from fourth on the reversed grid, but was leading by the end of the second lap and went on to chalk up his 10th victory at the Hampshire speedbowl.
The lofty West Countryman got up to third at the start, then cut inside Colin Turkington at the flat-out Village sweeper on the opening lap to move up to second.
Poleman Stephen Jelley was out front, but Cook pulled off an excellent move on the brakes to get ahead of the West Surrey Racing-run BMW 330e M Sport at the end of lap two.
Just as Dan Cammish had with Motorbase Ford team-mate Ash Sutton earlier in the day, Jelley played the team game to let team-mate Turkington in front as they headed up Woodham Hill on lap three.
But Turkington had no answer to Cook, who set fastest lap fourth time around to extend his advantage to over a second, and was two seconds in front by the end of lap eight of the 14 tours.
Cook took the chequered flag 2.682s in front, while Turkington’s second place means he has re-established himself as the sole series leader after entering the race tied on points with Sutton.
“The car was on another level,” said Cook, who was spun out by contact with Sutton in the opening race of the day.
“It was just unbelievable. I didn’t have a lot of tyre degradation, the balance was beautiful, and I got the tyres switched on quickly.”
Of the move on Jelley, he added: “To be fair to Stephen I got a really good run through Church, I just jinked out and he left a car width.”
Jelley completed a WSR BMW 2-3, but came under pressure late on from the Speedworks Motorsport Toyota Corolla of Rory Butcher, who once again made good progress on race day after struggling in qualifying.
Butcher, in turn, had Sutton looming large in his mirrors, the Ford Focus making a terrific early charge from 11th on the grid to fifth within three laps.
Tom Ingram ran fourth early on in his Excelr8 Motorsport Hyundai i30 N, but the title contender lost out in a chicane shemozzle in which he received a shove from Dan Rowbottom’s Team Dynamics Honda.
That dropped Ingram to sixth, and he lost that position to Rowbottom when the bearded Midlander pulled off a nice move around the outside of the chicane.
Michael Crees lost a stack of places on the first lap from third on the grid, but held on for eighth in his Power Maxed Racing Vauxhall Astra ahead of Gordon Shedden, who worked his Dynamics Honda past Dan Cammish’s Motorbase Ford on the final lap.
Title contender Jake Hill was run out wide onto the grass on the opening lap, and finished 12th in his WSR BMW.
BTCC Thruxton race three - 14 laps
1 | Josh Cook | Honda/TOCA | 18'07.311 | |
2 | Colin Turkington | BMW | 18'09.993 | 2.682 |
3 | Stephen Jelley | BMW | 18'12.155 | 4.844 |
4 | Rory Butcher | Toyota/TOCA | 18'13.354 | 6.043 |
5 | Ash Sutton | Ford | 18'15.165 | 7.854 |
6 | Dan Rowbottom | Honda | 18'15.490 | 8.179 |
7 | Tom Ingram | Hyundai | 18'18.124 | 10.813 |
8 | Michael Crees | Vauxhall/TOCA | 18'18.346 | 11.035 |
9 | Gordon Shedden | Honda | 18'19.345 | 12.034 |
10 | Dan Cammish | Ford | 18'20.077 | 12.766 |
11 | Dan Lloyd | Hyundai | 18'21.268 | 13.957 |
12 | Jake Hill | BMW | 18'21.508 | 14.197 |
13 | Ricky Collard | Toyota/TOCA | 18'21.971 | 14.660 |
14 | Ollie Jackson | Ford | 18'29.063 | 21.752 |
15 | Jack Butel | Hyundai | 18'31.190 | 23.879 |
16 | Tom Chilton | Hyundai | 18'32.183 | 24.872 |
17 | Ash Hand | Vauxhall/TOCA | 18'35.087 | 27.776 |
18 | Árón T.-Smith | Cupra/TOCA | 18'36.066 | 28.755 |
19 | Dexter Patterson | Infiniti/TOCA | 18'38.188 | 30.877 |
20 | Tom Oliphant | Cupra/TOCA | 18'38.304 | 30.993 |
21 | Jade Edwards | Honda/TOCA | 18'38.865 | 31.554 |
22 | Rick Parfitt | Infiniti/TOCA | 18'56.248 | 48.937 |
23 | Bobby Thompson | Cupra/TOCA | 18'24.885 | 1 lap /17.574 |
(23) | Adam Morgan | BMW | 17'38.947 | Retirement |
(25) | Jason Plato | Honda/TOCA | 13'28.315 | Retirement |
(24) | Aiden Moffat | Infiniti/TOCA | 9'33.481 | Retirement |
(27) | Nicolas Hamilton | Cupra/TOCA | 13'40.572 | Retirement |
(25) | George Gamble | BMW | 3'00.353 | Retirement |
(23) | Sam Osborne | Ford | 1'30.152 | Retirement |