The most outrageous tuner specials of all time

When more than enough power is just not hitting the mark, it’s time to call in the tuning companies. They have always offered upgrades from mild to wild, and it’s the extreme end of the tuning scale that grabs our attention here. Buckle up and hang on to find out about five of the most outrageous tuner cars ever made.  

Brabus 6.5 (W124)

Credit: Alexander Migl

Mercedes thought it had the super saloon box well and truly ticked with its 500E that was largely designed and built by Porsche. Brabus had other ideas, however, and reckoned the 500E’s 5.0-litre V8 with 326bhp was all a bit measly. The upshot was the Brabus 6.5 and, as the name suggests, it packs a much meatier 6.5-litre V8 snarling out 450bhp and 500lb ft of torque. 

This was enough to make even the AMG-tuned E60 ‘Hammer’ look a bit limp by comparison, and the Brabus 6.5 barrelled its way from 0-62mph in just 4.5 seconds. It also breezed past the 155mph limit imposed by Mercedes, as Brabus fitted the 6.5 with a bespoke wiring loom to do away with the limiter and equip the car with its own traction control system. 

As well as the engine and electronics, Brabus went the whole hog and fitted the 6.5 with a new automatic gearbox and limited slip differential to cope with the power. The only downside to all of this work was that it made the 6.5 incredibly expensive. You’d be extremely lucky to spot one in the classifieds today – the last time one appeared, it was listed at almost £430,000. 

Callaway Twin Turbo Corvette

 

Credit: Mr.choppers

Reeves Callaway wanted to be a racing driver but, like so many aspiring to motorsport greatness, his pockets were just not deep enough. As a result, he worked as a race instructor and quickly realised the cars he was driving didn’t have enough power to be really fun on the track. 

This was in the 1970s and turbocharging was emerging as the solution to gaining lots of power. Callaway was an early convert to forced induction and offered kits for Audi, BMW, Mercedes, and Porsche. However, it was a homegrown car that made this US tuner’s name famous when he launched the Callaway Twin Turbo Corvette. 

If one turbo was good, it followed that two would be double the fun. So it proved with the Callaway Corvette that arrived in 1987. This early version delivered an easy 345bhp and top speed of 178mph, and it was even offered through Corvette dealers with a full warranty. 

Power steadily increased throughout the life of the Callaway Twin Turbo Corvette, growing to 402bhp by the time the production run of 497 cars was done. However, the most outrageous part of this tuner’s range was the 880bhp ‘Sledgehammer’. It achieved a top speed of 254.76mph, making it the fastest street legal car in the world in 1988. Just as impressive is the car was driven 700 miles by road to the test track, set the record, and was then driven back home. 

Koenig Ferrari Testarossa

 

Credit: Koenig Specials

Willy Koenig has more than a fair claim to be the most outrageous tuner of the 1980s. His cars featured on bedroom posters, magazines features, and the driveways of the very wealthy. He’d turn his engineer’s mind to almost any make and engine, but the car that grabbed the most attention was his twin-turbo Ferrari Testarossa. 

No slouch when it left the Maranello factory, Koenig reckoned there was a lot more to come, and he was right. Where the standard Testarossa delivered 390bhp, Koenig could extract up to 1000bhp. Not all of the dozen Testarossas worked on by this German genius had the wick turned up so much and 700bhp was thought to be enough for most drivers. 

To keep all of the Ferrari’s power in check, Koenig also supplied the cars fitted with widened and firmer suspension to his own design. The brakes, exhaust, body, and interior also received Willy’s scrutiny and made his cars stand out even more than a standard Testarossa. If you fancy a Koenig Testarossa but can’t find one of the 12 originals for sale, amazingly Koenig still sells all of the bits to upgrade your standard Ferrari. 

Racing Dynamics K55

 

Credit: Racing Dynamics

Take BMW’s smallest car at the time and shoehorn in the biggest engine from the Bavarian firm. The result is the Racing Dynamics K55, a BMW Compact like no other you will ever see or drive. This Italian firm saw no reason why not to carry out this conversion to an unsuspecting 318ti and the engineering required to fit the V12 motor from an 850Ci was as impressive as the idea was unhinged. 

That would have been outrageous enough for the K55 to rank among tuner car royalty, but Racing Dynamics felt the standard 5.4-litre V12 was a bit lacking. To solve this, the engine’s capacity was increased to 5.5-litres to free up 427bhp. This was delivered to the back wheels via a six-speed manual gearbox and contemporary road tests remarked that the K55 was a little tricky to drive on the limit with that much power in a car with a relatively short wheelbase. On a dry road and with everything hooked up perfectly, the K55 was good for 0-60mph in 4.5 seconds and wouldn’t ease up until it was the far side of 170mph. Just as well it ditched the 318ti’s brakes in favour of a bespoke set-up. 

Ruf CTR Yellowbird

 

Credit – Ducktail964

The most influential tuner car of all time? Quite possibly, and the Ruf CTR Yellowbird can also lay claim to being the first car video to go viral when Stefan Roser drove this extreme Porsche 911 by the scruff of its neck around the Nürburgring. Watch the video, look past the tyre smoke, and you can see this is a very well developed car. 

Alois Ruf’s tuning firm had been improving Porsches since 1977, but for the CTR it threw everything it knew at the car. Rather than use a 911 Turbo as the base, the car’s shell is a 3.2-litre Carrera with the rain gutters shaved off to improve its aerodynamics. There’s just one door mirror for the same reason, while ducts in the rear wings channel vital cold air to the 3.4-litre turbocharged flat-six motor. It punches out a claimed 469bhp, though the company hints 550bhp might be nearer the mark, and made the Ruf CTR capable of 0-100mph in 7.3 seconds and a top speed of 211mph. 

A production run of 30 CTRs might make it more common than some tuner cars, but the Yellowbird easily ranks as one of the most outrageous. 

Ever dreamed of commissioning a money-no-object tuner special of your own? Tell us about it in the comments below…