. The reduction in displacement was largely an effort to meet CAFE requirements for fuel economy. Throttle-body fuel injection was now standard on Eldorado and Seville when equipped with the 368. Rear-wheel drive cars and the Commercial Chassis for hearse and ambulance builders used the Rochester Quadrajet 4-barrel carburetor. Cadillac referred to this new TBI (throttle-body fuel injection) system as Digital fuel injection (DFI); this particular induction system was later adopted by other GM divisions, except on Oldsmobile V8s, and was used well into the 1990s on GM trucks. Power output dropped to at 3600 rpm and torque to at 2000 rpm in DEFI forms as used on the front-wheel drive Seville and Eldorado but on the 4-barrel Quadrajet-equipped RWD models. This engine was standard on all Cadillacs except the redesigned Seville, in which it was optional. V8-6-4 For 1981 Cadillac introduced a new engine that would become notorious for its unreliable electronics, the V8-6-4 (L62). The L61 had not provided a significant improvement in the company's CAFE numbers, so Cadillac and Eaton Corporation devised a cylinder deactivation system called Modulated Displacement that would shut off two or four cylinders in low-load conditions such as highway cruising, then reactivate them when more power was needed. When deactivated, solenoids mounted to those cylinders' rocker arm studs would disengage the fulcrums, allowing the rockers to "float" and leave the valves closed despite the continued action of the pushrods. These engines are easily identified by their rocker covers, which each have elevated sections over 2 cylinders with electrical connectors on top. With the valves closed the cylinders acted as air-springs, which both eliminated the feel of "missing" and kept the cylinders warm for instant combustion upon reactivation. Simultaneously, the engine control module would reduce the amount of fuel metered through the TBI unit. On the dashboard, an "MPG Sentinel" digital display could show the number of cylinders in operation, average or current fuel consumption (in miles per gallon), or estimated range based on the amount of fuel remaining in the tank and the average mileage since the last reset. Another rare and advanced feature introduced with DFI was Cadillac's truly "on-board" diagnostics. For mechanics who had to deal with the 368s, the cars contained diagnostics that did not require the use of special external computer scan-tools. The new Electronic Climate Control display, along with the MPG Sentinel, provided on-board readout of any stored