Fernando Alonso insists McLaren has shown progress "in every area" in recent races but concedes it has been minimal.
Alonso completed only one lap at the Mexican Grand Prix, later saying he only started out of respect for the fans having been informed of a terminal engine problem before the race. McLaren team-mate Jenson Button was also using Honda's upgraded power unit but was still a long way off the pace, labouring to a 14th-place finish.
Alonso, who has not scored a point since Hungary in July, doubts this weekend's Brazilian Grand Prix will be much easier for McLaren but is confident the team will continue making progress.
"We knew Mexico would be tough, and many of Interlagos' characteristics are similar, with its steep sections and long straights," Alonso said. "However, the circuit is incredible to drive and always a lot of fun, so I'm looking forward to the weekend. We are still seeing progress in our pace and small improvements in every area race by race, so we know it's important to keep our heads down and keep pushing towards the end of the season.
"Every race counts and the more we can learn and gather data at every track, the more information we will have at our disposal over the winter and for the development of our package."
Alonso has never won at Interlagos, a circuit where he lost world championships in 2007 and 2012, and is keen to maximise his track time this weekend after a string of reliability issues at recent races.
"The last couple of races have been frustrating on my side of the garage, as we've had some bad luck with reliability issues. It's something we're always working hard on and we'll be looking especially closely at in the lead up to the Brazilian Grand Prix, so we can make sure we get the most track time possible over the course of the weekend."