Zagato developed first the L147 (or Super Diablo), which was conceived with a very aggressive design, featuring many aeronautic elements, typical of Zagato philosophy (the double-bubble roof and the big air intake for the rear V12 engine radiators).
The first Lamborghini Canto prototype
First spotted in high-speed tests on the Nardo circuit in Italy, Lamborghini had a problem with cooling down the big 6 Litre V-12 engine; the rear air intakes were terrifyingly big at the rear. However the speed was phenomenal. A rumored top speed of about 350 Km/h was mentioned.
First tests were done with a 510 Bhp engine 'borrowed' from the Diablo SV, but later the engine was replaced by a 6.0 Litre evolution of the Diablo SV-R block with about 600 horsepower to drive all four wheels. Developing a machine pumping out over 600 horsepower wasn't too difficult since the V-12 mounted in the Diablo SE30 Jota special did have 595 Bhp.
Several drawings were made before the original Canto design, which would lead to a running prototype, was ready; one of these was this unique-looking one, dating from around 1997. It clearly shows some Ferrari Testarossa influence in the side air intakes. Fortunately, this design was rather quickly dropped for a more exotic-looking one. The next, a purple finished example was already close to becoming the Canto, the big rear air intakes were present, although covered by vertical slats on this first drawing, they would later be removed, and big round intakes would come in their place just before a running prototype was built based loosely on this drawing.
Since the Audi takeover of Lamborghini in June 1998, the tests moved a little faster. The Diablo successor, it was hoped, would be ready for the 1999 production year at a suggested price of $250,000, production limited to only 400 units, all with rear-wheel drive.
The original design for the Canto was done by Norihoko Harada of SZ designs, a novelty for Lamborghini. Still, after initial tests, the rear end of the car had to be redesigned. The ugly oversized air intakes were replaced by smaller ones, probably incorporating some thermostatically controlled system to ram air into the engine compartment. The 'Naca' ducts on the side of some of the prototypes were fakes and were expected to be removed from the production model.
However, during October 1998, VW/Audi Chairman Ferdinand Piech judged the L147 project to lack the typical Italian look and Diablo's aggressive threat. He shelved the project, and several design companies were contacted to propose new designs for the Diablo successor.
Redesigned & revived in 1999
Audi Chairman Ferdinand Piech decided the 1998 Canto prototype was not what was expected of a Lamborghini, like the Diablo and the legendary Countach and Miura, so he halted the project. He was unhappy with the large, ugly rear air intakes and felt that the engine was not up to what should be expected of a pure supercar.
But during February 1999, the Lamborghini Design facility came up with a slightly modified Canto proposal. The front was facelifted, the headlight units remained almost identical, but the fog lights utilized more up-to-date poly-ellipsoïde technology. The turn indicators and driving lights were repositioned on top of the front wings instead of at the front of them as on the first Canto prototypes. However, the biggest changes were the rear; the top-mounted air intakes, now smaller and much better integrated into the sweeping lines of the Canto.
The complete engine was rethought; it remained the massive V-12, with a 6.0 Litre displacement, but the engine management and the complete electronics were changed, and the first tests showed a power increase up to 640 Bhp. According to the official press release, which Automobili Lamborghini SpA published at the end of January 1999, the production unit would be reduced to 610 Bhp. This way, the factory would maintain the same maintenance schedule as they used for the 530 Bhp Diablo's. In the same press release, Automobili Lamborghini SpA stated that this redesigned Canto prototype would be presented to the public at the 1999 Geneva Motor Show, and the Diablo would remain in production for two years. These two years would be needed to get the Canto fully developed for production.
Several interior designs were created, but at this time, nothing about the final looks had been revealed. However, the 1999 Geneva Auto Show didn't have anything resembling the Canto on display, Automobili Lamborghini didn't get the green light from Ferdinand Piech to show the nearly finished redesigned Canto from Zagato, and the project was finally canned.
It is rumoured a total of five Cantos were built, although some sources believe the same chassis was used for several of these prototype's, so it is probable that only three new chassis were built for the various Canto's. One of these prototypes, a black fully working example, is believed to have been shipped to Japan and is now in the hands of a private collector.
Work then turned to a completely new project, with the Diablo eventually being replaced in late 2001 by the Murcielago.
Sources: Mark Smeyers - LamboCars.com; all-about-lambo.narod.ru; Zagato