He returned the the track yesterday and completed a much longer stint in preparation for the opening race of the season - the Australian Grand Prix on March 17.
Hartley was dumped by Toro Rosso at the end of last season following his first full year with the team after joining in late 2017.
He recorded his first Formula One point at the Azerbaijan Grand Prix in April last year with a 10th placing. Hartley qualified second to last but moved into the top 10 when seven drivers failed to finish the race. The last time a New Zealand driver earned a Formula One point was Chris Amon at the 1976 Spanish Grand Prix.
Hartley followed that up with a 10th at the German Grand Prix in July and a career-best ninth in Austin. He had five retirements from his 21 races this year including a scary crash at the Canadian Grand Prix when he collided with Williams-Mercedes driver Lance Stroll and was pushed into a wall on the opening lap.