Ingram, who enters the weekend third in the points, whirled his Excelr8 Motorsport Hyundai i30 N around the Brands Grand Prix circuit to head the times by the huge margin of 0.397 seconds.
By contrast, the same gap encompassed the next 15 competitors, indicating how much of an advantage Ingram held.
The Hyundai appeared out of reach by a couple of tenths on old tyres in the second session, which was the only running to be held in fully dry conditions.
Ingram then emerged again to lop another two tenths off that in the closing stages, while Excelr8 Hyundai team-mate Dan Lloyd moved up into second place.
But Lloyd’s time was then pipped on the very final lap of the session, as the Hyundais headed for pitlane, by the Team Hard Cupra Leon of pre-weekend Jack Sears Trophy points leader Bobby Thompson.
“It was really good,” Ingram told Autosport.
“The car feels so hooked up it’s fantastic – it feels very similar to that Oulton Park car I had where it just came out of the box nice.
“I did a 30.4 on old tyres, then just did a balance check at the end [on new rubber] and only found two tenths.
“It’s a pleasure to drive, and it’s really important that Dan’s up there – he’s been shadowing us today in terms of set-up.”
Colin Turkington, fourth in the standings as he bids for a record-breaking fifth title, was towards the front in both sessions and ended up fourth in his West Surrey Racing-run BMW 330e M Sport.
Fifth was the Motorbase Performance Ford Focus of Dan Cammish, with Jason Plato – beginning the swansong weekend of his farewell BTCC season – in sixth position in his BTC Racing Honda Civic Type R.
George Gamble was seventh in the lead Ciceley Motorsport BMW, followed by the Team Dynamics Honda of Dan Rowbottom.
Ninth and 10th were the remaining two title contenders, with current points runner-up Jake Hill’s WSR BMW just ahead of the Motorbase Ford of Ash Sutton.
Championship leader Sutton was outside the top 20 when he took to the track for a final run – on his first push lap he ran wide through the gravel at Paddock Hill Bend, before putting it all together as the chequered flag appeared.
At the beginning of the first session the circuit was decidedly damp on the GP circuit from overnight rain, and it was still a bit sketchy as it drew to a close – Cammish put in a flier on the final lap to head Ingram, Rory Butcher and Sutton.
