Fernando Alonso reckons his LMP1 and IndyCar exploits boosted him as a driver and helped him record a career first by trouncing Formula 1 team-mate Stoffel Vandoorne in qualifying.
Alonso beat Vandoorne in every qualifying session in 2018 and was last outqualified in the 2017 Malaysian Grand Prix, a run of 26 races.
He is not expected to return to the grid after stepping away from McLaren for 2019 and billing the Abu Dhabi season finale as his F1 farewell.
Alonso, a two-time world champion and veteran of 311 starts, said his extracurricular activities in IndyCar and the World Endurance Championship in 2017 and 2018 played a role in achieving "something that I never reached in my career" in his final F1 season.
"It's difficult to know exactly your speed in the car," said Alonso. "You only can follow the numbers, and this year it has been my best year by far in terms of qualifying battles.
"So, I feel I'm competitive and I'm fast. Probably, a testing day in IndyCar and the WEC programme this year, I feel a better driver, or a more complete driver.
"I understand more the behaviour of the cars, other driving techniques, other ways of saving energy, saving the tyres.
"So, you have more information from the outside and other engineers, other points of view, that maybe makes you better, or [provides] a wider view of motorsport.
"Probably when you jump in the Formula 1 car, you have an extra opinion even if it's not totally useful in a Formula 1 car.
"The overall concepts of different philosophies, I think it helps you as a driver."
After Alonso's clean sweep, the next-best team-mate qualifying record this season was Charles Leclerc outqualifying Marcus Ericsson 17-4 at Sauber.
Toro Rosso pair Pierre Gasly and Brendon Hartley had the fewest comparable sessions, at 18 of 21, and Gasly won that fight 12-6.
Romain Grosjean enjoyed the narrowest margin, overturning a deficit to Kevin Magnussen to win the Haas battle 10-9.
Autosport's verdict on F1's 2018 team-mate qualifying battle
A comparison of each intra-team qualifying fight, based on sessions both drivers took part in and with anomalies such as reliability problems excluded (e.g. Grosjean's engine failure in Canada)
|Fernando Alonso||21||0||Stoffel Vandoorne|
|Charles Leclerc||17||4||Marcus Ericsson|
|Sebastian Vettel||16||4||Kimi Raikkonen|
|Esteban Ocon||16||5||Sergio Perez|
|Max Verstappen||15||3||Daniel Ricciardo|
|Lewis Hamilton||15||5||Valtteri Bottas|
|Nico Hulkenberg||13||6||Carlos Sainz|
|Pierre Gasly||12||6||Brendon Hartley|
|Sergey Sirotkin||12||8||Lance Stroll|
|Romain Grosjean||10||9||Kevin Magnussen|