M178
V8- 178.980 4.0 L · 3,982 cc
462 PS
340 kW · 456 hp bei 6,000 U/min
600 N·m
443 lb·ft bei 1,600 U/min
Mercedes-AMG GT Roadster (R190) · AMG GT Roadster
Open-top AMG performance — roof optional.

Mercedes-AMG introduced the GT Roadster on the R190 chassis with a three-layer insulated soft top that folded in eleven seconds, maintaining the aluminum spaceframe's rigidity through additional underbody bracing. The same twin-turbocharged 4.0-liter M178 V8 powered the range from the GT Roadster through the GT C and GT R variants, with power outputs reaching 585 PS. Without a fixed roof, the long bonnet and side-exit exhausts read even more dramatically — a front-engined roadster in an era dominated by mid-engine exotics.
The R190 AMG GT Roadster extended the dedicated AMG sports-car program into open-air motoring — a convertible built with the same single-minded performance focus as its C190 coupé sibling.

3 model designations across 2017–2019 — engines, chassis codes and production figures for the R190.
| Modell | Modelljahre | Baumuster | Motor | Getriebe | Gesamt |
|---|---|---|---|---|---|
| GT | 2017– | 190.477 | 178.980 | 700.402 | — |
| GT C | 2017– | 190.480 | 178.980 | 700.402 | — |
| GT S | 2019– | 190.478 | 178.980 | 700.402 | — |


The M178 as fitted to the R190.
462 PS
340 kW · 456 hp bei 6,000 U/min
600 N·m
443 lb·ft bei 1,600 U/min