"I spent most of the time in Switzerland and did quite a lot of training. I'm coming back feeling fresh and ready for the big challenge we have in the second half of the season," Sutil said.
Di Resta said he hoped to do start afresh this weekend.
"We need to get the car working for us like before. In Budapest it was difficult to drive, but sometimes you get those tough weekends. Since then we have regrouped and analysed the previous races properly and hopefully this weekend will be a fresh start. We usually do well in Belgium and everyone is determined to get back to the situation we had at the start of the year when we seemed to be punching above our weight," said di Resta.
"We know the car is mechanically sound and the drivers have been happy with it, so we need to unleash its potential. Getting on top of the new tyres is certainly a challenge and an area we are focussed on, but it's the same for everyone. With nine races to go and a close battle in the championship it's vital that we are competitive on all tracks," he said.