Jordan King took over from Rio Haryanto for Manor's final day of in-season testing at Silverstone on Wednesday.
The Brit, who won last Sunday's GP2 race, completed a total of 70 laps, running through the team's development program without any major issues.
"It was a really good day," King said.
"A relatively smooth one, so we had plenty of track time to achieve our objectives. Our morning session was slow-going, because we were working through some very specific aerodynamic tests with rakes on the car.
"So they were just out-and-in single lap runs, with modifications between each run and quite a bit of time in the garage.
"It’s painstaking stuff, but then I’m a Development Driver and that’s what I’m here for. In the afternoon we were able to get into more substantial runs while we evaluated some new mechanical developments."
Following some relative uncertainty regarding Rio Haryanto's immediate future with Manor, which appears to be secured at least in the short term, King was earmarked as a possible replacement.
The man from Harbury, Warwickshire would be more than happy to comply if he gets the call to race in Formula 1.
"I feel I’m perfectly ready to step into an F1 car. The first time I got in the car in Abu Dhabi was the shock of ‘I’ve actually driven an F1 car’, so at Barcelona it was a bit more chilled out.
"I actually knew what I was doing and it wasn’t ‘stars in your eyes’ so much. So I could focus more on doing the job."
REPORT: Raikkonen shows Ferrari pace on second day of test
Scene at the British Grand Prix
Silbermann says ... Radio Ga Ga
Keep up to date with all the F1 news via Facebook and Twitter
