car to use a semi-automatic transmission was the 1989 Ferrari 640. It used hydraulic actuators and electrical solenoids for clutch control and shifting, and was shifted via two paddles mounted behind the steering wheel. Another paddle on the steering wheel controlled the clutch, which was only needed when starting from a standstill. The car won its debut race at the Brazilian Grand Prix, but for much of the season suffered from reliability problems. Other teams began switching to similar semi-automatic transmissions; the 1991 Williams FW14 was the first to use a sequential drum-rotation mechanism (similar to those used in motorcycle transmissions), which allowed for a more compact design that required only one actuator to rotate the drum and change gears. A further development was made possible by the introduction of electronic throttle control soon after, which made it possible for the car to automatically rev-match during downshifts. By 1993, most teams were using semi-automatic transmissions. The last F1 car fitted with a conventional manual gearbox, the Forti FG01, raced in 1995. Following concerns about the potential for Formula One cars to shift gears automatically without any driver input, mandatory software was introduced in 1994 that ensured that gear changes only occurred when instructed by the driver. Pre-programmed, computer-controlled, fully-automatic upshifts and downshifts were re-introduced and allowed from 2001, and were permitted from that year's Spanish Grand Prix, but were banned again in 2004. Buttons on the steering wheel to shift directly to a particular gear (instead of having to shift sequentially using the paddles) are permitted. The 2005 Minardi PS05, Renault R25, and Williams FW27 were the last Formula 1 cars to use a 6-speed gearbox before the switch to a mandatory 7-speed gearbox for the 2006 season. Since 2014 season, Formula 1 cars currently use mandatory 8-speed paddle-shift gearboxes. The now-defunct CART Champ Car Series switched from a lever-shift sequential system to a 7-speed paddle-shift system for the 2007 season. This transmission was introduced with the new-for-2007 Panoz DP01 chassis. The rival IndyCar Series introduced their 6-speed semi-automatic paddle-shift system for the 2008 season, also replacing the previous lever-shifted sequential transmission, introduced with the Dallara IR-05 chassis for 2008. IndyCars currently use the Xtrac P1011 sequential transmission, which uses a semi-automatic paddle shift system supplied by Mega-Line called AGS (Assisted Gearshift System). AGS uses a pneumatic gearshift and clutch actuator controlled by an internal transmission control unit. Both the