February 1998 marked a very key date in the development of the Astra estate. Before the Mark 4 version was launched, 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 estate models were launched alongside the three and five door hatches and played second fiddle to the big-selling hatchbacks. Nevertheless there was plenty of choice available. Six engines were on offer: 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, CD and CDX. 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 estate was launched and sold at a reduced price over the Internet, while summer 2000 the 1.7-litre turbodiesel engine was 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 estate 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 common-rail diesel 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 This offered a smoother and more economical alternative to the somewhat outdated direct injection units with which Vauxhall had unsuccessfully tried to do battle against ever-more sophisticated Ford diesels.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.