The team added 42 laps to its weekend tally in Free Practice Three, before Sebastian and Lance embarked on a challenging qualifying session.
Sebastian focused on the Medium tyre compound for the first time this weekend in the early stages of FP3, and put in a best time of 1.21.306.
He switched to the Soft tyres towards the end of the session and improved to a 1.20.986 to finish the session in 19th.
For the start of the first part of qualifying, Sebastian started his running on a new set of Soft tyres.
Clocking the miles on Friday in Mexico
Sebastian and Lance got in their first laps of the Autodromo Hermanos Rodriguez as the Mexico City Grand Prix weekend got underway.
He did two flying laps on his first set. His first time was a 1.21.141, before he followed that up with a 1.20.990.
For his second run, he did two warm-up laps before his flying lap. He improved on his previous best in all three sectors and put in a 1.20.419.
Unfortunately, this was only good enough for 17th and Sebastian did not progress into Q2.
"Things did not look very promising in FP3 this morning, but we hoped we could take a step forward for qualifying.
"But that was not the case: we struggled for grip and overall balance – the car would not behave in certain corners. I know from past experience that the podium here is incredible – but that is a long shot right now. But who knows?
"I am always hopeful that we can do something special in the race tomorrow."
With a new set of Medium tyres, Lance put in a best time of 1.21.413 in the first half of FP3 as he got used to the middle compound.
He switched to a new set of Soft tyres at the end of the session, and improved to a 1.20.477, which was enough for 16th-fastest.
Lance started Q1 with a new set of Soft tyres, completing two flying laps.
With his first effort, he put in a 1.21.649. He then improved to a 1.20.761.
He returned to the pits for a fresh set of Soft tyres, for one final flying lap at the end.
He improved on both his personal best first and second sectors, and put in a 1.20.520, but this was only good enough for 18th.
With a penalty from the United States Grand Prix, Lance will start the race on Sunday from the back of the grid.
"We have really struggled for grip and balance here, which is why we are down the order this weekend.
"We have tried several things yesterday and today, but it has not turned our fortunes around. From our starting position, it is going to be a challenge to get into the points tomorrow.
"However, it is a long race, we perform better in those conditions, and we know that anything can happen."
Mike Krack, Team Principal
"It has been a bit of a struggle for us all weekend, and qualifying today was no exception.
"Both Lance and Sebastian complained of a lack of overall grip; no matter what changes we made to the car we just did not seem to be able to improve the overall balance and provide our drivers with a car that gave them confidence.
"With the margins around here so tight, lacking just a few tenths makes a big difference.
"Today, unfortunately, we were on the wrong side of that fight – but we know our car performs better in race conditions; this Grand Prix is often unpredictable, and both drivers will give it everything to fight for points tomorrow."
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