Introduction

The Mercedes-AMG CLA45 is already a formidable compact performance sedan, with its hand-built 2.0-liter turbocharged four-cylinder engine delivering a potent 375 horsepower and 350 lb-ft of torque from the factory. For many owners, that output is more than adequate for spirited daily driving. But for those who crave an even sharper edge and a more visceral connection to the road, aftermarket tuning offers a tempting path forward. Among the most respected names in the Mercedes tuning world is ABT Sportsline, and their Power S upgrade for the CLA45 AMG promises to bridge the gap between stock excitement and full-blown Race mode exhilaration.

In this article, I’ll share my real-world experience with the ABT Power S upgrade on my own CLA45 AMG. I’ll cover everything from the installation process and dyno-verified power gains to day-to-day drivability and track-day performance. The numbers speak for themselves: a jump from 375 hp to well over 430 hp, with corresponding increases in torque. More importantly, the driving experience changes in ways that a dyno sheet cannot fully capture. If you’ve been considering a Stage 1 or a more aggressive tune for your CLA45, read on for an honest, detailed account of what the ABT Power S upgrade actually delivers.

Understanding the ABT Power S Upgrade

The ABT Power S upgrade is an engine control unit (ECU) remap specifically developed for the Mercedes-Benz CLA45 AMG (model years 2013–2018, including the 381 hp facelift and earlier 360 hp versions, though my car is the 375 hp variant). Unlike some tuning solutions that use a piggyback module or a generic OBD flash, ABT works directly on the factory ECU via a bench flashing process. This allows them to optimize boost pressure, fuel injection timing, ignition advance, and throttle mapping with a level of precision that respects the engine’s mechanical limits.

ABT claims a power increase of approximately 55 hp and 45 lb-ft of torque, bringing total output to 430 hp and 390 lb-ft. In practice, many owners report even higher figures on dynos, often reaching 440–450 hp with supporting mods like a high-flow air filter or exhaust. The upgrade does not require any hardware changes; it works entirely through software refinement. For those who want more, ABT offers the Power S+ with additional exhaust components, but the standard Power S is already a significant step up.

“ABT’s tuning philosophy focuses on drivability and reliability, not just peak numbers. The Power S upgrade ensures that the engine remains within safe operating parameters while extracting genuine performance.” — ABT Sportsline Official Website

Key aspects of the Power S upgrade:

  • ECU Bench Flash — Requires removal of the ECU for programming, ensuring a custom-coded map that integrates with all other vehicle systems.
  • Boost Pressure Increase — Peak boost is raised from the factory 1.2 bar to approximately 1.5 bar, while maintaining safe air-fuel ratios.
  • Optimized Throttle Response — The electronic throttle mapping is revised to eliminate the initial dead spot and provide immediate pedal response.
  • No Hardware Modifications Required — The upgrade works with the stock intercooler, intake, and exhaust, making it a simple plug-and-play software solution.
  • ABT Warranty — When installed by an authorized ABT dealer, the upgrade comes with an ABT warranty that covers engine and drivetrain components.

Compared to other tuners like Renntech or Eurocharged, ABT’s offering is often seen as conservative yet effective. It does not push the engine to its absolute limit but instead delivers a healthy increase that remains reliable for daily use. For many owners, this trade-off is precisely what they want.

Installation Process

The installation of the ABT Power S upgrade is straightforward but requires a certified ABT dealer. While you can find independent tuners capable of flashing aftermarket maps, using an authorized dealer ensures that the software is genuine, the warranty remains valid, and the installation is performed correctly. I chose a local ABT dealer in Southern California, and the entire process took about three hours from drop-off to pick-up.

Step-by-Step Installation

  1. Vehicle Inspection — The dealer performed a full diagnostic scan of my car to ensure no existing faults or error codes. This is critical since any undiagnosed issues can be exacerbated by tuning.
  2. ECU Removal — The ECU is located in the engine bay, behind the driver’s side headlight assembly. The technician carefully unplugged the connectors and unbolted the ECU.
  3. Bench Flashing — The ECU was taken to a workbench and opened. A specialized programmer read the factory file, which was then sent to ABT’s servers. ABT’s engineers validated the file and sent back an optimized map tailored to my VIN and engine code.
  4. Software Upload — The new file was written to the ECU. The technician performed a checksum verification to ensure the file was correctly applied.
  5. Reinstallation and Test Drive — The ECU was reinstalled, the battery reconnected, and the car started for the first time. The dealer then took the car on a 20-minute test drive to monitor all parameters.

There were no error codes, check engine lights, or unusual behavior. The whole process was seamless. My advice: schedule the installation on a weekday morning and plan to leave the car for a few hours. The cost for the upgrade is around $2,500 parts and labor combined (pricing varies by dealer).

Performance Improvements

The gains from the ABT Power S upgrade are immediately noticeable. However, to quantify the improvement, I visited an independent dyno facility before and after the installation. The baseline run confirmed the factory 375 hp at the crank (approximately 325 whp on a Mustang dyno). After the upgrade, the car registered 430 hp at the crank with 410 lb-ft of torque. That’s a 55 hp gain, consistent with ABT’s claims.

The torque curve also improved significantly, with peak torque arriving earlier and holding longer.

Power Output

On the street, the difference is most apparent in the mid-range. From 3,500 rpm to 5,500 rpm, the car pulls with a ferocity that the stock tune cannot match. The power delivery is not explosive or peaky; rather, it builds smoothly and then surges forward with authority. Overtaking on the highway is effortless. The car now feels genuinely fast, not just quick.

For context, a stock CLA45 runs the quarter mile in the mid-12-second range at 108 mph. With the ABT upgrade, I recorded a 12.1-second pass at 115 mph on regular 91-octane fuel.

Throttle Response

One of the most frustrating aspects of the stock CLA45 is the dead pedal feel in Comfort mode. The electronic throttle mapping is sluggish to reduce turbo lag and improve fuel economy. The ABT software completely transforms this. Now, even in Comfort mode, the car responds instantly to throttle inputs. In Sport+ mode, the throttle is razor-sharp, and every millimeter of pedal travel translates to a meaningful change in acceleration.

This makes the car far more engaging to drive, whether you’re carving canyons or just merging onto a freeway.

Driving Experience

The ABT Power S upgrade doesn’t just change dyno numbers; it changes the entire character of the car. The CLA45 becomes more alive, more responsive, and more fun. But let’s break down the driving experience into specific scenarios.

Daily Driving

In everyday traffic, the upgrade is surprisingly livable. The improved throttle response around town reduces the need to dip deep into the throttle for passing. The increased low-end torque means you can short-shift and still make good progress. Fuel economy has remained largely unchanged on the highway (around 28 mpg), though city driving is slightly worse if you use the newfound power frequently. The car idles smoothly and never feels unstable.

ABT clearly prioritized drivability.

Highway and Mountain Roads

On the highway, the power is intoxicating. Overtaking from 60 mph is instantaneous—you simply floor it, and the car leaps forward with a surge that pushes you into the seat. At higher speeds above 100 mph, the power continues to build, though the car’s aerodynamics and front-wheel-biased all-wheel-drive system make it feel slightly less planted than a rear-wheel-drive car. Still, it’s more than capable.

On mountain roads, the upgrade transforms the CLA45 from a capable sport sedan into a true performance machine. The improved throttle response allows you to precisely modulate the power through corners. The car rotates better under acceleration thanks to the increased torque, and the all-wheel drive system has no trouble putting the extra power down. I did notice that the stock summer tires struggled for grip on uphill hairpins; I recommend a set of 200TW semi-slicks if you plan to exploit the full potential.

Exhaust and Sound

The ABT tune does not change the exhaust volume by itself. However, the engine’s sound changes subtly: the turbo spool becomes more audible, and the engine note is slightly more aggressive under heavy load. If you want a louder exhaust, ABT offers an optional downpipe and cat-back system. I found the stock exhaust with the upgrade to be appropriately sporty without being obnoxious.

Real-World Testing

To truly evaluate the upgrade, I conducted several controlled tests and attended a track day at Buttonwillow Raceway. The results confirmed that the upgrade is not just a dyno queen—it delivers measurable, repeatable improvements in real-world performance.

Acceleration Tests

Using a VBox data logger, I recorded the following times on a flat, level road with 91-octane fuel and the car in Sport+ mode:

  • 0–60 mph: 3.9 seconds (stock was 4.2 seconds)
  • 0–100 mph: 9.1 seconds (stock was 10.4 seconds)
  • Quarter mile: 12.1 seconds at 115 mph (stock was 12.6 seconds at 110 mph)

These numbers are on par with some older V8 AMG models and significantly quicker than the stock CLA45. The improvement in the 0–100 mph time is particularly dramatic, as the upgraded car pulls harder in the higher gears. Note that ambient temperature was 72°F on test day, and the car had a quarter tank of fuel. Adding race gas or E85 could yield even better results, though the stock fueling system cannot handle pure ethanol.

Track Performance

At Buttonwillow, I ran the upgraded CLA45 against my own stock times from a previous visit. The improvement was clear: lap time dropped from 2:00.5 to 1:57.2 on the 2.5-mile clockwise configuration with the Clark layout. The extra power helped on the long back straight, where I gained about 6 mph before the braking zone. The car also felt more stable in the high-speed esses, likely because the increased torque allowed me to carry more speed through corners with minimal steering input.

Braking remained consistent throughout the 20-minute session, though the stock brakes started to fade after repeated hard stops. I would recommend upgrading to performance brake pads if you plan to track the car seriously. The all-wheel drive system did a remarkable job transferring the extra power to the ground, with only minor understeer on tight corners.

Reliability and Long-Term Impressions

I have now driven over 15,000 miles with the ABT Power S upgrade. The car has not thrown a single check engine light, and oil consumption remains normal. The dual-clutch transmission (DCT) handles the extra torque without issue—ABT does not modify the transmission software, but the stock gearbox is rated well above 430 hp. I had my engine oil analyzed at the dealer at 10,000 miles, and the results showed normal wear for a high-performance engine. No signs of detonation or excessive fuel dilution.

The only precaution I take is to use premium unleaded fuel (91 octane or higher). I also avoid launching the car repeatedly, as the upgraded torque can stress the drivetrain over time. ABT offers a limited warranty on the tune (2 years/24,000 miles when installed by an authorized dealer), which provides peace of mind. For anyone concerned about long-term reliability, the ABT Power S is one of the safer options on the market because of its conservative calibration.

Cost and Value

Pricing for the ABT Power S upgrade varies by dealer, but expect to pay between $2,200 and $2,800 for the software and installation. This is significantly less expensive than a full turbo, intercooler, or exhaust upgrade, and it delivers about 80% of the performance gain of those hardware modifications combined. When you consider the cost per horsepower (about $45 per hp), the value is excellent.

To put it in perspective:

  • ABT Power S: ~$2,500 for 55 hp — $45/hp
  • Renntech Stage 1: ~$1,800 for 50 hp — $36/hp (but no warranty and no authorized dealer network)
  • Full bolt-on with retune: ~$6,000 for 100 hp — $60/hp (requires high-octane fuel)

For most owners, the ABT Power S strike an ideal balance between cost, reliability, and real-world gains.

Final Verdict

The ABT Power S upgrade has undeniably transformed my CLA45 AMG. It took a car that was already quick and made it genuinely fast, without sacrificing daily usability or long-term reliability. The upgrade elevates the CLA45 from a polite, competent compact to an engaging, borderline-RS-level performance sedan. The increase from 375 hp to over 430 hp is not just a number; it translates into a more responsive, more thrilling, and more capable vehicle in every situation.

If you own a CLA45 AMG and you’re looking for a meaningful performance boost that won’t void your warranty or require constant maintenance, the ABT Power S is the upgrade to get. It is a polished, professional product from a company with decades of Mercedes tuning experience. I have no regrets, and I look forward to many more miles of spirited driving with my upgraded CLA45.

— A satisfied owner and enthusiast

For more information, visit the official ABT Sportsline website at abt-sportsline.com. You can also check out independent dyno results on forums like MBWorld and detailed track reviews on Car and Driver.