Defending champions Craig Lowndes and Jamie Whincup secured top spot for Team Vodafone after the first day's practice for the Supercheap Auto Bathurst 1000 as they seek to secure a hat-trick of wins at Mount Panorama.

The Ford duo were less than a second outside Greg Murphy's lap record and finished clear of Murphy and Jason Richards in the first of the Sprint Gas Racing Holden Commodores. Ford Performance Racing duo Mark Winterbottom and Steven Richards were third fastest.

Completing the top five after the three practice sessions was the HSV team of Rick Kelly and Paul Radisich and veterans Russell Ingall and Paul Morris fifth in the Supercheap Holden team.

All the leading teams were 'happy' with the opening day of running aside from a joking Ingall.

"I just can't stand all this happiness. Everyone's happy," Ingall said. "Our car's a mongrel, we're struggling, we don't know what we are going to do. I'm really hating life. No, actually we're 'happy' too."

Whincup was pleased with speed of the Vodafone Falcon in the opening practice session, with the car proving to be quick with both old tyres and the set of greens late in the session.

"We had a great day," he said. "It's very early days yet. It's my seventh time here and the first time I have had a run with greens on and it was thrilling going over the top of the mountain.

"We feel very comfortably going into tomorrow."

It was a welcome return for Murphy and Jason Richards, who have had wretched fortune in their new Holden this year, completed when they blew an engine at Phillip Island.

"It's the best car we've had all year," Murphy said. "The car felt pretty good and we are quite excited about the rest of the weekend. As you know it's been a real struggle for us this year."

Winterbottom and Richards were equally pleased with the day's work.

"The car went well," Winterbottom said. "The track was a bit different and I think with a busy night tonight we will have it really good for tomorrow."