Honda chief ‘relieved’ that engine now runs
Jenson Button completed 35 laps on Wednesday to bring McLaren's tally for the week up to 79, before he was slowed by a fuel-related spark/ignition issue in the afternoon.
"Looking back at the first four days of testing, I'm both happy and relieved that we've been able to get the car here and watch it run on the track," said Arai.
"It's a new car and a new power unit, so a huge undertaking for many people in both Sakura and Woking.
"Of course, we'd anticipated there would be issues – this is a test, after all – but the difficulties we faced here were more than we'd expected, so we weren't able to get the running time we'd ideally wanted.
"Nonetheless, Fernando Alonso and Jenson's feedback has been positive and comprehensive – they've given us some very good information.
"There's now an incredible amount of positivity within the organization. We'll return to the track in Barcelona – with some modifications – and will be stronger at the next two tests."