The Mitsubishi Eclipse Ralliart concept, shown in 2005 at SEMA, was a one-off performance prototype built to show what a rally-inspired Eclipse could look like. It featured custom carbon-fiber bodywork, all-wheel drive, and a turbocharged 4G63 engine borrowed from the Lancer Evolution, producing around 400 hp.

The MG X11 concept, shown in 2001, was a preview of the performance-focused MG ZT-T estate based on the Rover 75 platform. The production MG ZT-T followed shortly after and was built between 2001 and 2005, offering sportier styling and suspension compared to the standard Rover 75.

The DC Design DC Star from 2005 was a custom two-door version of the first-generation Porsche Cayenne Turbo S created by Indian coachbuilder DC Design. Rather than being an official factory concept from Porsche, it was a coachbuilt showcase built around the Cayenne Turbo S platform and shown at events like the Dubai Auto Show. The DC Star took the normally four-door Cayenne SUV and reworked it as a two-door, more dramatic body style with bespoke exterior and interior touches

The MG XPower SV-R, released in 2004, was the top-performance version of the XPower SV. It was powered by a Roush-tuned 5.0-liter, 32-valve Ford Modular V8 that made a claimed 385 hp. Only 82 XPower SVs were built in total before MG Rover went into receivership in 2005. The exact number of SV-R versions is unclear, but only a small portion of the total production were SV-Rs, making them especially rare.

The Studiotorino RUF RK Spyder, shown in 2005, was a heavily modified version of the Porsche Boxster styled by Studiotorino and tuned by RUF. It used a supercharged 3.8-liter engine producing around 434 bhp, giving the small roadster serious supercar-level performance. Only 49 were built, making it very rare.

In the mid-2000s, Volvo offered the XC90 with a DOHC 32-valve V8 engine developed by Yamaha. In 2005, Volvo showed a supercharged version of the XC90 V8 at the Los Angeles Auto Show, hinting at a higher-performance model. That supercharged version was never sold to the public. The standard XC90 V8 remained on sale for a few years before the V8 option was discontinued in 2011.

The Mercury Meta One concept, shown in 2005, was a luxury crossover that previewed a diesel-hybrid powertrain. It was meant to signal a new direction for Mercury, blending upscale design with more efficient tech. The car never made it to production, and the Mercury brand was later discontinued before anything like it reached showrooms.

The Fiat Croma 8tto V, created in 2005 by Italdesign Giugiaro, was a one-off, high-end version of the Fiat Croma crossover. It was fitted with a Maserati-sourced V8 engine, turning the practical Croma into an over-the-top luxury performance concept that was never meant for production.

The Lotus Circuit Car Prototype, shown in 2005, was a track-only version of the Lotus Elise built for extreme performance. It weighed just 650 kg and used a supercharged VVTL-i engine. Thanks to its low weight and added power, it could sprint from 0–60 mph in about 3.5 seconds and reach 0–100 mph in around 9 seconds.

The Acura RL A-Spec concept, shown in 2005 at the Detroit Auto Show, previewed the A-Spec Performance Package that was later offered on the second-generation Acura RL (KB1). The KB1 RL was the North American version of the fourth-generation Honda Legend. It shared the same all-wheel-drive system, which Acura marketed as Super Handling All-Wheel Drive (SH-AWD).

The ASC Helios 300, shown in 2005 at the North American International Auto Show in Detroit, was a convertible version of the Chrysler 300C. There were rumors it might be sold as a limited-edition model, but it never went into production.

The Citroën C-Métisse concept, shown in 2006 at the Paris Motor Show, was a four-door coupe prototype with dramatic rear-hinged butterfly doors. It featured an early diesel hybrid setup, combining a diesel engine with electric motors to deliver strong performance while improving efficiency.