When Jonas “JKDesign” Kakarikas unveiled his latest creation on May 9, 2025, the Saab community collectively sat up. No Saab had ever left the factory with power sent to the rear axle—until now. Over the past three years, Jonas has taken a discarded 2000 Saab 9-5 Aero, stripped it to its skeleton, and rebuilt it from the ground up with a bespoke rear-wheel-drive system. In yesterday’s milestone video, he confirmed that Swedish authorities have granted full road approval, marking the world’s first street-legal RWD Saab 9-5 Aero.
Table of Contents
- 1 From Cheap Donor to Road-Ready Prototype
- 2 Engineering the RWD Transformation
- 3 Certification Challenge: Passing Swedish Inspection
- 4 Powertrain and Performance Specs
- 5 Retaining OEM Integrity and Practicality
- 6 Why This Saab Project Matters
- 7 Watch the Build in Action
- 8 The Road Ahead for RWD Saab Enthusiasts
From Cheap Donor to Road-Ready Prototype
In June 2022, Jonas acquired his project car—a sunroof-equipped Aero that wore fading paint, rust-eaten dog-leg panels, and a battered interior full of holes. It was nearly worthless as a donation vehicle, but the engine block remained solid, fueling his vision. Rejecting off-the-shelf modifications, Jonas committed to a fully OEM-compatible transformation: the factory dashboard, center console, and interior electronics would all remain functional, untouched by aftermarket hacks.
Over 56 dedicated build videos, Jonas documented every obstacle—from sourcing a custom driveshaft to fabricating new mounting points for the rear axle. He enlisted support from family, specialist shops, and sponsors, pushing through late-night problem solving and iterative testing. No compromise was made on build quality: even the seat belt pretensioners and airbag sensor circuits were reconfigured to work flawlessly after structural modifications.
Engineering the RWD Transformation
Swapping a rear axle into a unibody sedan designed for front-wheel drive presents immense challenges. Jonas began by relocating the battery to the trunk, clearing space for a custom-made driveshaft tunnel. A bespoke central tunnel box replaces the original flat floor panels, housing both the propshaft and an Opel Omega fuel tank for balanced weight distribution.
To mate the Saab engine to the new rear differential, Jonas engineered a custom adapter plate and coupler, ensuring drivetrain angles remained within tolerance. Heat shielding and reinforced transmission mounts protect against vibration at high rpm. The suspension geometry received equal attention: adjustable coilovers and bespoke trailing arms maintain precise camber and toe under load, delivering controllable handling despite 406 brake horsepower pushing the rear wheels.
Certification Challenge: Passing Swedish Inspection
Gaining approval from the Swedish Transport Agency demanded rigorous proof of safety and compliance. Jonas submitted engineering drawings, fatigue-testing reports, and emissions data, convincing inspectors that his modified 9-5 Aero met all criteria for crashworthiness and pollution standards. On May 9, 2025, officials cleared the vehicle for registration—an unprecedented feat for a drivetrain swap of this magnitude.
Inspectors sampled the turbocharged exhaust at E85 blend levels and verified structural integrity around the welded reinforcements in the floor pan. Jonas demonstrated full functionality of factory safety systems, including ABS, traction control, and side-impact airbag sensors. The build’s uncompromised OEM electronics played a key role in securing street legality without concession to aftermarket ECUs.
Powertrain and Performance Specs
Under the hood, the original 2.3 TI-engine remains largely untouched, save for upgraded internals to handle E85’s higher octane rating. Jonas retained the factory turbo manifold but retrofitted a larger Garrett unit capable of over 600 bhp. For registration purposes, the ECU is currently detuned to 406 bhp—well within legal limits—yet the hardware supports future upgrades without further inspection.
The rear differential, sourced from a high-Torque GM truck unit, locks seamlessly under acceleration, channeling torque to the 18-inch wheels shod in grippy Michelin Pilot Super Sport tires. Braking duties rely on Saab’s stock Aero rotors, augmented by upgraded Brembo calipers at the rear axle. 0–60 mph arrives in under 4.5 seconds, a benchmark virtually unmatched by any factory front-wheel-drive sedan of its era.
Retaining OEM Integrity and Practicality
Throughout the build, Jonas prioritized the 9-5 Aero’s daily usability. All stock controls in the center console operate as designed, from climate control to the multi-info display. He preserved the original sunroof mechanism, repurposing its wiring harness to power the relocated battery’s charging circuit. Even the glove box latch and cup-holder dimpling remain untouched.
Cargo capacity survives thanks to the slimline custom fuel tank and compact differential placement. Jonas reports “room for the entire family,” with rear-seat legroom equivalent to the unmodified chassis. No hack-job aesthetic mars the interior or exterior: carbon fiber accents are tastefully integrated, and color-matched side skirts conceal reinforced chassis sections.
Why This Saab Project Matters
For Saab enthusiasts, this build rewrites the brand’s engineering rulebook. It proves that the 9-5 platform can exceed its front-wheel-drive heritage, blending Saab’s reputation for safety and comfort with pure rear-wheel-drive dynamics. The project revives interest in the model among tuners who previously dismissed front-wheel drive as a handling liability.
Moreover, Jonas’s transparent documentation—56 episodes spanning the build—offers a blueprint for fellow hobbyists. His approach balances meticulous planning with on-the-fly problem solving, showcasing how to adapt modern performance parts without sacrificing factory reliability. This 9-5 Aero stands not as a one-off stunt but as a proof of concept for future conversions.
Watch the Build in Action
Two-year milestone: the recap that marked a turning point
In a video posted ten months ago, Jonas shared a comprehensive recap of the build’s first two years, highlighting the major milestones, design pivots, and key challenges. This video marked a turning point in the project, capturing the transition from concept to functioning prototype. For anyone new to the journey, it’s the best way to understand the level of commitment and craftsmanship that shaped this groundbreaking Saab:
To experience the full journey—from its humble beginnings to the triumphant road-legal debut—watch Jonas’s detailed walkthrough:
Be sure to subscribe to his channel for technical deep dives on fabrication techniques, suspension tuning, and ECU calibration tailored for Saab platforms.
The Road Ahead for RWD Saab Enthusiasts
With registration secured, Jonas plans to shake down the chassis on public roads and track sessions, refining suspension settings and power delivery. Future videos will cover dyno testing, alignment clinics, and driver impressions under high-speed conditions. Enthusiasts can expect detailed guides on sourcing parts, adapting existing Saab components, and overcoming certification hurdles.
This build also opens the door for aftermarket specialists to offer RWD conversion kits. Interested parties should consult the Swedish Transport Agency’s approval guidelines and reference Jonas’s engineering package for compliance strategies. As the first street-legal RWD Saab 9-5 Aero, this Aero sets a new performance benchmark—one that merges Saab’s engineering DNA with the exhilaration of rear-wheel drive.
Wow, that’s some serious dedication, number of obstacles and small or big issues is unimaginable. Would love to drive RWD Saab, that has to be some unique experience. Big respect to the owner!