Before the Mark 4 version was launched in February 1998 the Astra had, for a long time, been a makeweight, a car that justified its own existence purely on fleet finance balance sheets. There was no logical reason for a private buyer to choose an Astra, because there were so many better options about, and Vauxhall realised this, knowing they had to raise their game. When the new range was unveiled, UK buyers realised it was worth the wait, for the car was demonstrably better than anything in its class. The Astra held this position for a mere eight months until the launch of the Ford Focus, but although the Astra had to give second best to the all-conquering Ford, it was still an excellent car.
The range initially consisted of three and five-door hatchbacks and five-door estates. Seven engines were available: a 90bhp 1.4i 16v, a 75bhp 1.6i 8v, a 100bhp 1.6i 16v, and 115bhp 1.8i 16v petrol units and 68bhp 1.7 turbodiesel and 2.0-litre direct injection diesel units. Trim levels started at Envoy, and ascended through Club, LS, Sport, CD and CDX. In September 1998 the 136bhp 2.0-litre SRi model was added, and in November the four-door saloon range was introduced. December 1998 saw the advent of Bi-Fuel versions which ran on Liquid Petroleum Gas (LPG) as well as regular unleaded petrol.
In October 1999 a new .com version of the Astra 1.6i was launched, sold at a reduced price over the Internet and available in five door hatch or estate forms, while summer 2000 saw the launch of the stylish Astra Coupe. With a roofline vaguely reminiscent of the much-loved Calibra coupe, this two-door Astra, with styling by Bertone, has exploited a niche uninhabited by the Focus. The 1.7-litre turbodiesel engine was also replaced by a more advanced turbocharged direct injection unit of similar capacity, and an intercooled 2.0Dti engine was introduced alongside the regular 2.0-litre direct injection diesel.
For the 2001 model year, the entry-level 1.6-litre engine's power was upped to 85bhp, while the 1.8 developed 125bhp. The 2.2-litre engine seen in the Astra Coupe and sporty VX220 roadster was also introduced to the mainstream range. Comfort and Elegance trim levels replaced CD and CDX respectively in autumn 2001 at a time when the rest of the Astra range enjoyed a boost in standard equipment levels. Spring 2002 saw the introduction of the 190bhp Astra SRi Turbo as the king hot hatch in Vauxhall stable. 2003 saw some minor variations to equipment levels but the big news was Vauxhall's first foray into the common-rail diesel market with their 1.7-litre CDTi powerplant. This offered a smoother and more economical alternative to the somewhat outdated direct injection units with which Vauxhall had unsuccessfully tried to do battle against ever-more sophisticated Ford diesels. The mark 5 Astra arrived to replace the mark 4 in the summer of 2004.