When Lamborghini showed their Diablo Roadster prototype on the 1992 Geneva Auto Show, orders began flowing in, but suddenly Lamborghini decided not to built this convertible Diablo. The customers who already placed their order were refunded, but this wasn't taken for granted by all of them. Some customers turned to Walter Koenig, a German based high-end car tuner who became famous, or notorious, with his ultra wide Ferrari conversions.
His Ferrari TestaRossa Special featured a 1000 Bhp (!!!) quad-turbo charged engine, after he presented the two door version, he also created a convertible Ferrari. With these cars in mind, converting a Diablo into a Roadster couldn't be too difficult for him, so two very wealthy customers contacted him to built a Diablo Roadster for them.
It took Walter Koenig about 3 months, but the result was stunning, he created an almost identical replica of the Diablo Roadster Prototype, the two fortunate people were very impressed with their final car. But one of them even wanted more, the yellow Diablo featured on this page took the Roadster idea one step further, Koenig designed a complete body kit for the Diablo.
He redesigned the front air dam, installed a new rear bumper/spoiler combination and completed the restyle with a new exhaust system. The engine was tuned to pump out over 600 Bhp by using two turbo's and the engine cover needed to be redesigned to be able to cool the engine down. Koenig also contacted OZ to get 18 inch versions of the famous five-hole wheels, but they refused to deliver them to Koenig, OZ may only build these wheels under contract for Lamborghini, who have an exclusivity clause in the contract. So Koenig only painted the crest of the wheel in the car's exterior color.
If you ordered the Koenig Roadster, two helmets were delivered with it, because the windscreen is hardly worth the name, the helmet was a real good idea. This tuned Roadster was shipped to his owner in Japan, and the current status is completely unknown.
During the time Automobili Lamborghini SpA didn't offer the Roadster yet, Koenig made several open-top replica's, some using the same roof configuration as the yellow one shown on this page, with the low front windscreen, but Walter Koenig also proposed a kind of Targa version for the same price of US $ 250.000.
This Targa version still used the full front windscreen, so driving this configuration is less troublesome than the full spider version, although complete bodywork and engine tuning was available on both kind of cars.
Koenig also modified the interior of the Diablo, as usual a complete custom made leather interior was available, but more important, Koenig altered the dashboard console, it became smaller and more integrated into the overall dashboard. Also a small diameter custom steering wheel could be installed.
I also found some images of a closed version of the Diablo Koenig, these had a special rear wing installed, resembling the wing later used on the Diablo SE30. I located a Fujimi 1/24th scale kit of the car I do know of at least two Diablo with the bodywork added to them, but I don't know if these specific cars actually got the engine tuning too.