2,995 mm (118 in) (until 1976) 3,045 mm (120 in) (post-1976 truck) 3,090 mm (122 in) (post-1976 Van)
1,295 mm (51 in)
1,615 mm (64 in)
In September 1971 the fourth generation Hijet appeared, with all-new sheetmetal, initially available only as a truck. The engine remained the ZM 360 cc two-stroke two-cylinder, while the rear suspension reverted to a live, leaf-sprung unit.In February 1972 a new Van was presented, originally marketed as the "Slide Van" as it now featured sliding doors on both sides in addition to a top-hinged tailgate. In September 1974 the front clip and rear bumper underwent light changes to accommodate full-size yellow license plates (hitherto, kei cars had been equipped with smaller plates than normal).
In October 1976 the four-stroke Hijet 550 appeared, with the new 550 cc AB20 engine taking full advantage of the recent new kei regulations. Bigger bumpers meant that all Hijets built after this date are slightly longer, as the 360 received the same external changes simultaneously, including a new front clip. To reflect the new engine, the 550 received the new chassis code S40. In export trim, where it was sold as the Daihatsu 550 Cab and Cab-Van, this engine has 30 PS (22 kW) at 5,500 rpm, and 4.2 kg·m (41 N·m; 30 lb·ft) at 4,000 rpm. The 550 Van had an advantage of a higher carrying capacity than the 360 Van, at 350 rather than 300 kg (772 and 661 lb).
Less than a year after the introduction of the 550, the wider and longer Hijet Wide 55 (S60) appeared, but the Hijet 550 continued in production and even underwent a facelift in April 1979 and now carried a blacked out grille. In April 1981 the four-stroke S40 Hijet 550 was discontinued, but the two-stroke S38 continued to be available until August 1981 as a low-cost version (by which time the sixth generation Hijet was already on sale). The later ZM-engined versions had 24 PS (18 kW). The two-stroke was also popular in many Southeast Asian markets, where emissions regulations were more lax and its lower purchasing price had a bigger impact.