The Ultimate is powered by the classic Mezger block air-cooled, twin-turbo motor as well, but the later 3,600c version with the appropriate Ruf modifications. This engine is rated at 590hp at 6,800rpm, with 720Nm of torque at 4,500rpm, and drives the rear wheels, or optionally all four wheels, through a six-speed manual gearbox.

In a car weighing just 1,215kg (DIN), this makes for a power-to-weight ratio of just 2.06kg/hp and quite spectacular performance, with a top speed of 212mph or 339km/h. Acceleration is equally impressive, with the all-wheel-drive variant capable of a sub-3.0 sec 0-100km/h sprint.

However, where the earlier torsion bar suspension is really on the limit with big horsepower, the newer coil sprung underpinnings of the Ultimate lap it all up, even in rear-drive form.
More than that, the modern twin-turbo technology coupled to fully mapped Motronic fuelling, spark and boost control is so devoid of turbo lag that this near 600hp monster of an engine can be trickled along in a high gear at relatively low speeds without problems.

The chassis feels totally in tune with the motor, and the car feels solid and well pinned down on the road. The counterpoint is that this light car is more pointy and eager to change direction, diving into corners more keenly than a steel bodied 911, yet with the feeling that you can trust it’s handling and grip. In short, this very fast machine inspires driver confidence.

With a power-to-weight ratio of 2.27kg/hp, the SCR 4.2 is a quick car capable of 322km/h or 200mph, and passing the 100km/h benchmark in around 3.3 sec on the way.

The linchpin of this 964-lookalike’s special bodyshell is Ruf’s in-house conversion that extends the wheelbase of the basic 993 shell by 70mm for improved high-speed stability. The car now has the same wheelbase as a 997 Carrera within an unchanged overall length.

The process is not as straightforward as it sounds, and is far more than just a cut and shut job like your average stretched limousine. Here, two incisions were made in the 993 shell to achieve the 70mm wheelbase extension. The first moves the front axle and wheel housings 20mm forward, while the second moves the rear axle and wheel housings 50mm aft. Because this prototype is steel bodied, the new rear wheel arches had to be fabricated by hand and took significant time and skill to get right.

This Geneva Show car is a steel bodied prototype, but the production cars will have carbon-fibre body panels to reduce kerb weight to 1,190kg (DIN)

The front suspension is McPherson strut, and the back end is the multi-link system from the 993-generation car. The use of the 993-style rear end was the reason for using a 993 shell as the core of this project, but even so, the mounting points on the frame are modified, and some of the suspension components are bespoke Ruf parts, as are the springs, dampers and anti-roll bars. To stop excessive lateral movement, the bushes are the uprated units from the 993 RS/GT2.

Just a quick reminder how a 911 should sound under 3000 rpm...

Just finished two days with these beauties by @rufsince1939 . Hard to put into words but I will try with the next posts