Passage: The Chevrolet Volt concept car debuted at the January 2007 North American International Auto Show, becoming the first-ever series plug-in hybrid concept car shown by a major car manufacturer. The Volt concept vehicle had four doors with a rear liftgate and seating for four passengers. This was a significant change in design when compared to the General Motors EV1 of the 1990s, which only seated two to reduce weight and to make the necessary room for the lead-acid battery pack. The top speed was also increased on the Volt, from the electronically limited 80 miles per hour (130 km/h) to 100 miles per hour (160 km/h). The battery pack size was reduced, from about 10.6 cu ft (300 L) in volume in the EV1, to 3.5 cu ft (100 L) in the Volt.General Motors' then-Vice-Chairman Robert Lutz said the two-seater sports car being developed by Tesla, the Tesla Roadster (2008), and the rapid advancement of lithium-ion battery technology inspired him to push the carmaker to develop the Volt after the 2006 Detroit Auto Show, overcoming internal opposition. Lutz's initial idea was to develop an all-electric car, but Jon Lauckner, General Motors Vice President for Global Vehicle Development, convinced him that to avoid an expensive battery, range anxiety concerns, and lack of public charging infrastructure, they could use a smaller battery pack with a small gasoline engine driving a generator acting as a backup to extend the range, but without a mechanical connection between the gasoline engine and the drive wheels, so it would be a pure electrically driven vehicle without many of the limitations General Motors learned from the EV1 experience.

Question: How many people could sit comfortably in the Volt concept car?
four