On a day in which one of their drivers announced he was quitting the team for Holden, V8 Supercar newcomers Mercedes appear to have finally found some speed.

Mercedes driver Lee Holdsworth was second fastest in Friday practice for the Sandown 500 behind Holden’s Craig Lowndes as the Erebus Motorsports team had a breakthrough day in Mercedes’ first year in the sport.

But it coincided with young gun Tim Slade announcing he was quitting Erebus at season’s end to join Holden – where he is likely to replace retiring Russell Ingall at Supercheap Auto Racing.

Slade was quick in the opening two practice sessions, before Holdsworth put an exclamation point on the day with a sizzling lap in practice three.

It took a new practice lap record from Lowndes in the dying seconds of the session to bump off the Mercedes – the Red Bull Racing driver clocking 1min 8.9334sec to Holdsworth’s 1:08.9613.

Ford driver Steve Owen, who will partner Will Davison in a Ford Performance Racing car in Sunday’s 500km race, was third fastest.

Both Lowndes and Holdsworth put their slick practice form down to good test sessions at Queensland Raceway last week in the lead-up to Sandown and next month’s blue-ribbon endurance round, the Bathurst 1000.

“It’s not surprising because we had a really successful test day last week,” Holdsworth said.

“We took a different direction and it worked. But (in) practice we’ve been in the top 10 the last couple of rounds and it all goes out the door in qualifying.

“I’m hoping we can repeat it tomorrow.”

A standard qualifying session will be only a part of the puzzle on Saturday, with drivers and co-drivers both playing a part in determining the grid make-up for Sunday’s 500km race.

The qualifying session will shape the grid for the first of two qualifying races, involving co-drivers only.

The co-drivers’ finishing order in the first 20-lap qualifying race will determine the grid for the main drivers in qualifying race two, and then their finish positions will be the grid positions for Sunday.

Mercedes and fellow newcomers Nissan will also receive some advantage for a perceived lack of race speed with four compulsory pit stops for all cars in Sunday’s race.