You're looking at the most powerful Mercedes-AMG production car ever made.
For years, rumors have circulated that Mercedes-AMG was cooking up a high-performance plug-in hybrid version of the GT 4-door Coupe. Likely to be dubbed the GT73 according to recent patent filings, last year, the Mercedes-AMG GT73 was teased in a video celebrating AMG's achievements in 2019, but now prototype testing appears to be underway.
Our spies have spotted what appears to be a prototype of the GT73 undergoing cold-weather testing in Northern Sweden. At first glance, it looks like the regular Mercedes-AMG GT 63 S, but a closer inspection reveals a hidden charging port on the camouflaged bumper indicating we're looking at the new GT73 hybrid. Put simply, this will be the most powerful production model Mercedes-AMG has ever produced.
While the name is a reference to the 7.3-liter V12 that powered the Mercedes-Benz SL 73 AMG and the Pagani Zonda, the GT73 is expected to adopt the same 4.0-liter, twin-turbo V8 as the GT63 and GT 63 S.
In the GT63 S, this powertrain produces 630 horsepower and 664 lb-ft of torque, enabling the high-performance four-door coupe to sprint from 0-62 mph in 3.1 seconds and top out at 195 mph. Thanks to electrical assistance, the GT73 will receive a considerable power boost, potentially increasing the output to over 800 hp.
With all that extra power, the GT73 should be able to comfortably do the 0-62 mph sprint in under three seconds, allowing it to compete with the Porsche Panamera Turbo S E-Hybrid. For comparison, Porsche's electrified powertrain produces 677 hp, enabling the Turbo S E-Hybrid to accelerate to 62 mph from a standstill in 3.2 seconds and max out at 192 mph.
Like the AMG GT 63 S, power will be sent to all four wheels through a nine-speed automatic transmission. Now that Mercedes-AMG has been caught testing the GT73, it shouldn't be too long before the automaker releases some more official teasers to build our anticipation. A debut date hasn't been confirmed yet, but the Mercedes-AMG GT73 should debut later this year.