at 15.2 seconds. Soon, performance enthusiasts determined the modifications that worked and the Grand Nationals easily broke into the 13-second territory. All Grand Nationals had the Lear Siegler-made cloth/leather interior which was only available for this year. An estimated 200 of the 1984 Grand Nationals were produced with the Astroroof option which makes these the rarest of the Grand Nationals. For 1986, a modified engine design with air-air intercooling boosted the performance even further to a specified at 4000 rpm and of torque at 2400 rpm. The Grand Nationals (quantity 5,512) and T-Types (quantity 2,384) were both produced in 1986. For 1987, performance reached and of torque. Buick dropped the T-Type package for Regal for 1987 models and opted for a "T" sport package instead. There were only 7,896 turbo Regals produced in 1986. In 1987, when turbo Regals reached their peak in popularity, a total of 27,590 turbo Regals were produced through December, with those models produced between September and December of that year window stickered as "1987½ Buick Grand National" vehicles. For 1987, a lightweight WE4 (Turbo-T) option was offered. Only 1,547 of this variant were produced. The differences between a WE4 and the Grand National were the interior trim package, wheels, exterior badging, aluminum bumper supports, and aluminum rear drum brakes as opposed to the Grand National's cast iron, making the WE4 a lighter and faster car. The rear spoiler was only available as a dealer-installed option. 1987 was the only year that the LC2 turbo option was available on any Regal, making it possible to even see a Limited with a vinyl landau roof and a power bulge turbo hood. Turbo Regal Limiteds were one of the rarest models of turbo Regals produced second only to the GNX at 1,035 turbo Limiteds. Turbo Regal Limiteds could be ordered with many options with most having chrome external trim but for $35 could have been built with the full black-out trim WO2 option making them extremely rare (similarly, a base Regal could also be ordered with the Turbo 6, and, the WO2 blackout trim was also available; all rare). Limiteds were treated to a very luxurious interior with plush carpeting and optional bench pillow seats and a column shift. It was also possible to order the 1987 Regal T with the 5.0/307 V8 instead of the turbo 3.8/231 V6. The 1987 model would be the end of the