Mercedes S320 CDI L Complete Review And Used Buying Guide

The Mercedes S320 CDI L represents the pinnacle of executive car engineering, blending a smooth V6 diesel engine with the renowned S-Class refinement. Launched as part of the W221 generation around 2006-2007, this long-wheelbase variant offers unmatched space and comfort for long journeys, making it a favorite among business executives and families alike.

Engine Power and Performance

At the heart of the S320 CDI L is a 3.0-liter V6 turbo diesel engine producing approximately 235 horsepower and strong torque delivery for effortless acceleration. This unit revs smoothly without the typical diesel clatter, pulling just 1,600rpm at motorway speeds for quiet cruising. In acceleration tests, it achieves 0-60mph in around 8 seconds, closely matching BMW’s 730d while prioritizing composure over outright speed.

Real-world performance shines on highways, where overtaking is seamless thanks to the broad torque band. Urban driving reveals its relaxed nature, though it’s not designed for aggressive track work. Braking is a highlight, stopping from 70mph in under 46 meters, showcasing Mercedes’ safety engineering.

Ride Comfort and Handling

Mercedes engineered the S-Class chassis for supreme isolation from road imperfections, using advanced air suspension (AIRMATIC) that adjusts to load and conditions. The long-wheelbase L model enhances rear passenger space, absorbing bumps with poise while maintaining stability at high speeds.

Handling is predictable for such a large car, with precise steering and minimal body roll. It’s not a sports saloon but excels in grand touring, where refinement trumps agility. Owners praise its ability to cover 375+ miles effortlessly, achieving over 42mpg on mixed routes.

• Key Comfort Features: Adaptive damping, quiet cabin, and heated/ventilated seats.
• Excellent for family trips with simple controls and vast legroom.
• Minimal vibrations, even under hard acceleration.

Interior Quality and Space

The cabin exudes luxury with high-grade leather, wood trims, and intuitive controls. Space is generous, especially in the L version, accommodating adults comfortably in all seats. Simplicity in displays and buttons reduces driver distraction, ideal for long hauls.

Build quality feels bulletproof, though some note minor cost-cutting in plastics compared to earlier S-Classes. Rear entertainment options and climate zones make it perfect for chauffeured duties or family outings.

Fuel Efficiency and Running Costs

Exceptional economy is a diesel standout, with figures around 30-42mpg combined, peaking near 50mpg on motorways per official claims. Real-world tests show 10-12L/100km (23-28mpg) in urban settings, impressive for a 2-tonne saloon.

Priced at £59,885 for the L model (2007 era), it’s pricier than rivals but holds value well. Maintenance requires specialist care due to complexity, but low fuel costs offset this.

Safety and Technology Features

Mercedes pioneered innovations like PRE-SAFE, radar cruise control, and multiple airbags. The S320 CDI L scores top in crash tests, with robust structure and stability control. Tech includes COMAND infotainment, though dated by modern standards.

Pros and Cons

• Pros: Unrivaled refinement, spacious interior, strong economy, powerful yet smooth engine.
• Cons: High purchase price, potential repair costs, less dynamic than BMW.

Buying Advice for Used Models

Today, W221 S320 CDIs are bargains under £10,000 with FSH. Check for suspension issues, turbo health, and rebuilt clusters—a common fix. Remaps boost power to 260+hp safely. New tyres, brakes, and MOT add peace of mind.

Comparison with Rivals

Against BMW 7-Series, the Merc prioritizes comfort over sportiness. Audi A8 offers Quattro traction but less space. The S320 CDI L wins for diesel serenity.

Owner Experiences

Owners rave about its joy on road trips, calling it ‘the best car ever’ for space and ease. Reliability varies; diligent maintenance yields trouble-free motoring.

Frequently Asked Questions (FAQs)

Is the Mercedes S320 CDI L reliable?

With proper servicing, yes—focus on air suspension and electrics. Many exceed 200,000 miles.

What is the fuel economy like?

Expect 35-45mpg on highways, lower in city driving.

How does it compare to petrol S-Class models?

Diesel excels in torque and economy; petrol suits shorter, spirited drives.

Is it suitable for families?

Absolutely—vast space, comfort, and simplicity shine on long trips.

What’s the best engine in W221 S-Class?

S320 CDI for balance of power, refinement, and costs.