Cat Racing's Simon Wills endured tough wet conditions to finish 15th and 9th in the final two races of the V8 Ultimate at Melbourne's Sandown International Raceway today.

After starting 18th in the opening race today, Wills held on to finish 15th despite entering the race with a dry suspension set-up to take advantage of the possibility of clearer weather.

For race two, the team fitted a full wet set-up and Wills enjoyed improved traction on board the Cat Falcon to move through the pack to finish 9th.

He could have even finished higher but suffered a fuel surge with only one lap to go when he was challenging for 8th place.

With heavy rain striking the circuit, the third race began under the safety car and Wills' race was made tougher when the team lost radio communication.

"It was certainly very hard out there today, but the car was a lot better in the final race and I really enjoyed the challenge," Wills said.

"It was very difficult to see because the front and rear screen started to fog up.

"We have demisters on both screens, but the vision - particularly when you are following another car - was very poor.

Wills positions of 18th, 15th and 9th put him in 11th place for the weekend.

"We are certainly not happy with the overall result, but the important thing for me this weekend was to finish all three races get more laps under my belt," Wills said.

"I was able to keep out of trouble and gain more experience in a wide range of conditions.

"That will stand me in good stead for next year. The Cat team have done a fantastic job this weekend and I was thrilled to get the chance to drive the car."

Today's races were won by Holden's Todd Kelly and Ford's Craig Lowndes. Kelly took the overall round victory ahead of Lowndes and Marcos Ambrose.