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Mercedes-Benz · Convertible / Roadster · 2016–2020

Mercedes-Benz SLC R172

Weaknesses, engine ratings and buying advice

★★★★★
2.3 / 5.0 · Based on 3 engine variants
Most Fun Engine

252–435 PS

3.0-3.5L V6 Benzin

V6 BiTurbo Roadster — Sonorous, Then Shrieking

Legendary!
Problem Engine

120–204 PS

2.1L Diesel Diesel

6 weaknesses

Stay Away!

Engine Overview

The Mercedes-Benz SLC R172 is available with 5 engine variants — from 120 to 435 hp. 1 variants had engine changes — the model year is crucial.

SLC 250 d · Diesel· 204 PS
2016 2017
Stay Away! 6 weaknesses
Show all weaknesses →
AMG SLC 43 · Benziner· 367–390 PS Engine Change
2016 2018
Be Careful 10 weaknesses
Show all weaknesses →
2018 2020
Be Careful 10 weaknesses
Show all weaknesses →
SLC 180 · Benziner· 156 PS
2016 2020
Be Careful 6 weaknesses
Show all weaknesses →
SLC 200 · Benziner· 184 PS
2016 2020
Be Careful 6 weaknesses
SLC 300 · Benziner· 245 PS
2016 2020
Be Careful 6 weaknesses
Show all weaknesses →

The Mercedes-Benz SLC 250 d (Diesel, 204 PS) has the OM651DE22 (2.1L Diesel) — rated: "Stay Away!", 6 known weaknesses.

The Mercedes-Benz AMG SLC 43 (Benziner, 367–390 PS) comes with 2 different engines: M276 (2016–2018, Be Careful) und M276 (2018–2020, Be Careful). Pay attention to the model year for the AMG SLC 43!

The Mercedes-Benz SLC 180 (Benziner, 156 PS) has the M274 (1.6-2.0L Turbo) — rated: "Be Careful", 6 known weaknesses.

The Mercedes-Benz SLC 200 (Benziner, 184 PS) has the M274 (1.6-2.0L Turbo) — rated: "Be Careful", 6 known weaknesses.

The Mercedes-Benz SLC 300 (Benziner, 245 PS) has the M274 (1.6-2.0L Turbo) — rated: "Be Careful", 6 known weaknesses.

Vehicle Weaknesses

WeaknessCost
!Vario roof leaking -- water ingress in rain

As with the predecessor SLK R171, the SLC R172 (facelift from 2016) also develops leaks at the vario roof when seals age or become brittle through UV exposure. The sealing of the metal folding roof in the area of the roof rails requires regular maintenance.

Symptoms: Damp interior after rain, water stains on headliner, musty smell
from 60,000 km
Ad Variodach gasket SLC R172Dachkinematik SLC 172Abgasketsset SLC R172
 High

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Known Problems and Issues

A total of 28 weaknesses have been documented for the Mercedes-Benz SLC R172 (2016–2020) — 22 engine-related and 6 vehicle-related. One problem engine: OM651DE22 (2.1L Diesel). Typical issues affect Body, Suspension, Electronics, Interior.

SLC (OM651DE22, 2016–2017) — Stay Away!: Chain Tensioner Seal Leaking — Recall, Timing Chain Stretch (Simplex Chain), Piezo Injector Faults. Power: 204 PS.

SLC (M274, 2016–2020) — Be Careful: High-Pressure Pump Faulty or Noisy, Camshaft Adjuster Leaks — Oil in Wiring Harness, Electric thermostat failure. Power: 156 PS.

SLC (M274, 2016–2020) — Be Careful: High-Pressure Pump Faulty or Noisy, Camshaft Adjuster Leaks — Oil in Wiring Harness, Electric thermostat failure. Power: 184 PS.

SLC (M274, 2016–2020) — Be Careful: High-Pressure Pump Faulty or Noisy, Camshaft Adjuster Leaks — Oil in Wiring Harness, Electric thermostat failure. Power: 245 PS.

SLC (M276, 2016–2018) — Be Careful: Oil cooler leaking in the V-block, Camshaft adjuster leaking — wiring harness contaminated, Piston slap (early 3.5L variants). Power: 367 PS.

SLC (M276, 2018–2020) — Be Careful: Oil cooler leaking in the V-block, Camshaft adjuster leaking — wiring harness contaminated, Piston slap (early 3.5L variants). Power: 390 PS.

What to watch out for with the Mercedes-Benz SLC? See the detailed listing of all engine and vehicle weaknesses in the sections above.

Frequently Asked Questions

What problems and weaknesses does the Mercedes-Benz SLC R172 have? +
The Mercedes-Benz SLC R172 has 22 known engine weaknesses and 6 vehicle weaknesses.
What should I look for when buying a used Mercedes-Benz SLC R172? +
faq.watch_a_avoid
Which engine is recommended? +
Be careful: M274 (1.6-2.0L Turbo), M276 (3.0-3.5L V6). No engine is rated 'Good Choice'. The most fun to drive is the M276 (3.0-3.5L V6). Problem engine: OM651DE22 (2.1L Diesel) — stay away!
Which Mercedes-Benz SLC R172 engine is the most fun? +
The {code} ({displacement}) offers the most driving fun in the Mercedes-Benz SLC R172 — rated: "Legendary!". {description} 367 hp BiTurbo in the most compact AMG roadster. The engine sings gloriously from 2,500 rpm and above becomes typical AMG shriek — open-top directly into the ear. Enormous torque from idle, 9G-Tronic sometimes overwhelmed. Compared to the SLK 350 a different league: the turbo charge gives the V6 a force the naturally aspirated engine never knew. Rare and sought after.
Is the Mercedes-Benz SLC R172 worth buying used? +
Caution is advised with the Mercedes-Benz SLC R172 — 1 of 3 engine variants are rated 'Stay Away!'. The engine choice is crucial.
What horsepower variants are available for the Mercedes-Benz SLC R172? +
The Mercedes-Benz SLC R172 is available with engine variants from 120 to 435 hp. Petrol: M274 (1.6-2.0L Turbo), M276 (3.0-3.5L V6). Diesel: OM651DE22 (2.1L Diesel).

Last updated: February 2026 · All information without guarantee