Driving their Mitsubishi Evo 8, the Pukekohe pair had a scare at the end of the first timed day in Dunedin on Tuesday when overheating issues forced an overnight head gasket change.
The car then ran faultlessly yesterday, with Inkster easily winning all seven stages contested.
On Tuesday, they were pushed hard by fellow Mitsubishi pair Jason Gill and Mark Robinson and Subaru duo Leigh Hopper and Simon Kirkpatrick.
However, a high-speed off in the final stage on Tuesday saw Hopper follow five-time event champion Tony Quinn and his co-driver Naomi Tillett into retirement before the start of the second leg yesterday morning.
Quinn said in a video posted on Facebook that his Lamborghini Huracan was ''not badly damaged but damaged enough that we couldn't run it''.
He hoped to have it back on the road tomorrow morning, or ''at the latest'' Saturday, he said.
Gill was forced to miss four of the seven stages yesterday morning after blowing an oil pressure sensor on his Evo 9's motor and having to wait while a replacement was found and fitted.
Modern 2WD classic category front-runners Clark Proctor and co-driver Sue O'Neill were also in the wars, with Proctor rolling his Nissan V6 turbo-engined Escort.
He got going again in the first stage of the day over Mt Cargill, north of Dunedin, then slipped to 17th in class after gearbox problems in the repeat of the Windsor/Tokarahi and Duntroon/Ngapara morning stages west of Oamaru yesterday afternoon.
When the field arrived back in Dunedin last night, Inkster had extended his overall lead over modern 2WD class leaders Gavin and Amy Riches to almost two and a-half minutes and their lead in the Allcomers 4WD drive class to over four and a-half minutes from fellow former gravel rally front-runner Todd and brother Rhys Bawden, of Hamilton, in a Mitsubishi Evo 10.
Defending Targa winner Dunedin's Martin Dippie and co-driver Jona Grant edged forward in the order in their Porsche GT3 RS, claiming their first modern 2WD class stage win in the second stage and ending the day second to the similar but more developed GT3 Porsche of the Riches.
The event continues with more stages today in and around Dunedin this morning.
After a service park and lunch at Milton, the field heads south to Invercargill. It moves through to Cromwell tomorrow before a final day in and around Queenstown on Saturday.
