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is always deployed at high speeds but avoids unnecessary opening and closing at lower and medium speeds. A switch in the engine compartment allows the spoiler to be raised for cleaning purposes while the car is at rest.

Other external aerodynamic modifications include the front and rear wrap-around deformable plastic sectionsthatcoverthebumpers ala928 and 944 Turboand door sills that also improve the airflow. Smooth rain gutters along the A-pillars make a contribution as well as the bonded windshield. Finally, the new 16-inch flat- surface polished aluminum wheels meet aerodynamic needs as well as providing for the space requirements of 4wd and ABS.

4WD—the heart of the matter

The central concept of the Carrera 4 is, of course, its full-time, automatic four-wheel-drive system based on experience gained with the 959. While the 959 4wd system is perhaps the ultimate in sophistication, it is also too expensive for series production and Porsche chose the variation so successfully used on the 1984 ParisDakar cars for the Carrera 4.

The difference between the Porsche system and traditional mechanical solutions lies in the electronically-

ABS compatibility. Under normal driving conditions, torque is divided 31 percent to the front axle and 69 percent to the rear. Wheel revolutions are picked up by the ABS sensors in each wheel and constantly compared in the computer. When rear wheel slip is sensed, the center (or longitudinal) differential diverts a greater proportion of the drive torque to the front wheels. The rotation speeds of the front and rear wheels are almost balanced, wheel slip is reduced and the tendency to oversteer diminishes. (The rear wheels are deliberately left with slightly more wheel spin to preserve the typical character of the rear-engined 911.) The moment the wheel sensors signal stability, the original 31/69 torque distribution is restored.

The second feature of the Porsche four-wheel-drive system is its adjustable transverse differential which comes into play during cornering. On extremely tight corners where there is a high degree of lateral acceleration (centrifugal force) and sudden weight transfer, every vehicle tends to turn into the bend. In the Carrera 4, the wheel sensors report this critical state and the transverse lock is activated forcing both rear wheels to turn at the same speed. This builds up a torque that combats the tendency to turn into the bend. The transverse lock is released when vehicle handling is normal again.

If either the longitudinal or the transverse differen

The 3.6-liter Carrera 4 engine with new exhaust system is fitted into the Carrera 4 inside a noisereducing capsule. More than 80 percent of the parts

for the Carrera 4 engine

are new.

controlled differential locks and the system’s perfect

PORSCHE PANORAMA