Mercedes‑Benz SLC R172 Engines — The Complete UK Guide
Every engine fitted to the R172 roadster — from the 1.6‑litre M274 to the 3.0‑litre V6 M276 in the SLC 43 AMG. Real UK replacement costs, honest reliability data, and the two‑seat roadster ownership realities that define this generation. Backed by real UK R172 enquiries in 2025 [MB‑VERIFIED].
Explore R172 Engines
Mercedes‑Benz SLC R172 Engine Codes — The Complete Database
Every engine fitted to the R172 SLC specifically — spanning the facelift SLC era (2016–2020) with four‑cylinder and V6 options.
Overview
Mercedes‑Benz SLC R172 — Overview
The R172 SLC is the facelifted third‑generation compact roadster from Mercedes‑Benz, produced from 2016 until 2020.
Originally launched in 2011 as the SLK‑Class, the R172 received a significant 2016 facelift that brought the SLC name — aligning it with the C‑Class with which it shared technology — along with updated styling, a revised engine line‑up, and the 9G‑Tronic transmission. The SLC range was powered by a selection of turbocharged four‑cylinder petrol and diesel engines, topped by the V6‑powered SLC 43 AMG.
Key Facts
Platform
Mercedes‑Benz R172
Predecessor
R171
Successor
None (discontinued)
Sibling body styles in this generation
None (standalone roadster)
Market Intelligence
The SLK/SLC range (R172 combined) generated real UK engine enquiries in 2025 [MB‑VERIFIED], with the OM651 diesel and M276 V6 commanding the strongest specialist interest.
Best & Worst Engines
Best Petrol Overall
M276 3.0‑litre V6 bi‑turbo (SLC 43 AMG, 367hp)
“The 3.0‑litre V6 bi‑turbo is the engine the SLC deserved — 367hp, 520Nm, and a soundtrack that transforms the compact roadster into a genuine AMG. It's the most rewarding engine in the range, with proven reliability across the Mercedes‑Benz line‑up.”
Who it's for: enthusiasts who want genuine AMG performance in a compact package.
Best Diesel Overall
OM651 2.1‑litre four‑cylinder turbo (SLC 250 d, 204hp)
“The 2.1‑litre turbo diesel delivers 204hp and 500Nm — ample torque for the lightweight R172 chassis. It's the most economical engine in the range, with a proven track record across the Mercedes line‑up. Timing chain and injector seals are the main watchpoints.”
Who it's for: buyers who want roadster fun with diesel running costs.
Highest Risk
M274 1.6‑litre turbo (SLC 180, 156hp)
“The entry‑level 1.6‑litre turbo is the least powerful engine in the range — 156hp in a roadster that deserves more. Timing chain stretch is a documented issue on higher‑mileage examples, and it lacks the character of the larger engines.”
Who it's for: buyers on a tight budget who prioritise running costs over performance.
Most Expensive Failure
M276 3.0‑litre V6 bi‑turbo (SLC 43 AMG, 367hp)
“The V6 bi‑turbo is the most complex engine in the SLC range — cooling system and turbocharger issues are documented on higher‑mileage examples, and the tight engine bay makes repairs labour‑intensive. A full recon is a four‑figure bill.”
Who it's for: AMG buyers with a maintenance budget to match the performance.
Best Value
M274 2.0‑litre turbo (SLC 200, 184hp)
“The 2.0‑litre turbo delivers 184hp and 300Nm — plenty of performance for the lightweight R172 chassis. It's the sweet spot in the range: more power than the SLC 180, lower running costs than the SLC 300 or V6, and the same proven M274 architecture.”
Who it's for: buyers who want genuine roadster performance without the V6's running costs.
Most Overlooked
M274 2.0‑litre turbo (SLC 300, 245hp)
“The SLC 300 is often overlooked in favour of the SLC 43 AMG — but 245hp from the 2.0‑litre turbo is more than enough to exploit the R172's chassis, and it avoids the V6's higher running costs. It's the performance bargain of the range.”
Who it's for: buyers who want near‑AMG performance without the AMG maintenance premium.
Mercedes‑Benz SLC R172 — Ownership Economics
The R172 rule
A £2,800–£4,800 OM651 recon against a £10,000–£18,000 R172 sits at 16–48% of the car's value — well inside the 70% Mercedes‑Benz threshold. Against a £8,000 high‑mileage example, the same recon reaches 35–60% — still viable, but a significant proportion of the car's residual value. A £4,500–£7,500 M276 recon against a £12,000 SLC 43 is 38–63% — on a high‑mileage example, that's borderline. Value the car and its service history first.
Common Problems
R172 Engine Replacement Costs — By Engine and Condition
Core Variants
Core Variants
Diesel Variants
Petrol Variants
Scope note: All variants listed are R172 SLC facelift (2016–2020) only. Pre‑facelift SLK models (2011–2015) are covered on their own Generation Page.
Market Intelligence
Most Requested E90 Engines (2025)
Most Requested E90 Variants
Average E90 Replacement Cost
Most Common E90 Failures
FAQ
Why UK Mercedes‑Benz SLC R172 Owners Trust MercedesEngines.uk
Trusted R172 Engine Suppliers
every garage and engine rebuilder in our network is vetted, rated and reviewed by real R172 owners, as part of the Engine Finders network.
Compare R172 Engine Replacement Companies
see prices, warranty terms and supply‑and‑fit options side‑by‑side before you commit.
UK Engine Replacement Services for R172
covering every variant from SLC 180 to SLC 43 AMG, with supply‑only or full supply‑and‑fit available nationwide.
Find the best Mercedes‑Benz SLC R172 engine replacement UK drivers rely on. Compare real prices from trusted specialists on EnginesMarket today and get back on the road with confidence.
