He was able to test a roomier version of the car at Silverstone yesterday, although he had to be towed back to the pits after spinning in hail and sleet.
The former world champion, who missed the first two races of the season, was relieved to get in a few laps at the wheel of the modified McLaren- Mercedes.
The team have confirmed that his new, specially redesigned car, is on schedule to enable him to race in the San Marino Grand Prix, at Imola on 30 April.
Mansell missed the first two races because his 5ft 10in, 167lb frame was too big for the new Mercedes MP4-10. The team has been working extra shifts at its Woking factory to produce a car in time for the San Marino Grand Prix.
The new, more spacious version of the car, named the MP4/10B, is nearing completion and is scheduled to undergo a required crash test on Monday.
"It looks like Mansell is going to run it for the first time at Imola on the Thursday before the race," Jocelyne Bia, of McLaren, said. "Everything is going according to plan."
Mansell's return will relegate Mark Blundell to the sidelines. Blundell drove for in the first two races, finishing fourth in Brazil. Mika Hkkinen remains the team's other driver.Reuse content