Mercedes continue pre-season testing

He set a quickest time of 26.2s during the recent tests - getting within striking distance of the Ford/Cosworth powered racecars.

Meanwhile PacWest drivers Mauricio Gugelmin and Mark Blundell were half a second quicker than they managed during Spring Training in early January.

However reliability is still believed to be a concern, with Blundell lucky to keep his Motorola Reynard off the wall following an engine failure in Turn Three.

Ilmor Engineering USA vice-president Paul Ray said: "To be honest, almost all the engines went the mileage we hoped they would.

"You have to push these things over the limit to find out where you stand. We had a few problems, but all the engines were over-mileage.

"Any engine failure is not a good thing, but we were encouraged that all of them went beyond a race distance.

"Overall, I'm fairly encouraged. I'm not jumping up and down by any stretch of the imagination; but we had been struggling to get the mileage we needed.

"Now we're managing to get them over a race distance, and that's all you need going into the first race."