Car makers that no longer offer any new showroom models with manual gearboxes include Volvo, Mercedes-Benz, Jaguar and Lexus.
Out of 300 models currently available to UK buyers, only 89 are manuals - 18 per cent fewer than last year.
At its current rate of decline, experts say that by 2029 the manual gearbox could be all but extinct like chokes, cassette players and wind-up windows.
The demise of the manual is being fuelled by the era of electric vehicles, which are all automatic.
The comprehensive study by online marketplace Car Gurus reviewed the UK's 30 most popular car brands.
It found that new manuals on sale fell from 194 in 2018 to 89 this year - a drop of 54 per cent.
Jeep, Land Rover, Mini and Honda offer only one manual option in their ranges.
Volkswagen offers the most with ten, followed by Ford and Hyundai, each with six.
Data from the Society of Motor Manufacturers and Traders shows that over three quarters - 76 per cent - of new car sales were manuals in 2011.
By last year, that figure had fallen to fewer than three in ten vehicles - 28.7 per cent.
Manuals to have ceased production include the UK's all-time best-selling car, the Ford Fiesta, which left the assembly line for the last time in July 2023.
Learner drivers are also opting for automatics during their driving tests in greater numbers than ever before, accelerating the demise of the manual gearbox.
There were a record 324,064 automatic-only tests taken last year, according to official Driver and Vehicle Standards Agency figures.
That was an increase of a third since 2022 and 269 per cent more than the 87,844 automatic-only tests taken a decade earlier.
They accounted for 37 per cent of the 865,000 driver qualification checks carried out last year.
CarGurus has compiled a guide on its website to some of the best new cars still available with a manual gearbox.
They include the Kia Picanto as a city runaround; Seat Ibiza as a small hatchback; Ford Puma for a small SUV; Skoda Octavia Estate for a large family car; and Mazda MX-5 as a sports car.
CarGurus says that second-hand car buyers can save an average of 14 per cent - or £3,466 - by opting for a manual.
Researchers compared the prices of 2020 models listed on the site for the 30 most popular car brands.
A 2020 manual Citroen C3, for instance, costs an average of £12,442 compared to £15,743 for an automatic - a saving of 21 per cent.
Meanwhile, a Volkswagen Polo is £18,285 (compared to £15,736, a saving of 14 per cent); a Nissan Qashqai £20,223 (£18,006, 11 per cent); and a Ford Fiesta £17,189 (£15,730, eight per cent).
Chris Knapman, editor at CarGurus UK, said: 'Between the increasing consumer demand for cars with an automatic gearbox and the rapid expansion of new EV models coming to market, we could be approaching the end of the road for the manual gearbox.
'Historically, manual gearboxes have found favour for their lower cost compared to automatics, as well as their more responsive nature and improved fuel economy.
'However, updates in technology mean that many modern automatics are at least as efficient as a manual alternative and much more responsive than the systems fitted in years gone by.
'It is likely that manual gearboxes will continue to hold a special place in the hearts of enthusiast drivers for the greater interaction they offer.
'And of course, manual cars will continue to be in strong supply on the used market in years to come.
'For those prepared to change gears themselves, opting for a manual car can also be a shrewd money-saving move.'