Built on the Epsilon platform, the Opel Vectra C of March 2002 was initially available as a four-door sedan (saloon) and a five-door hatchback, known as the GTS. A five-door station wagon (estate) was added in 2003. The Vectra C's official début was at the 2002 Geneva Motor Show. Originally, the Vectra C was due to début with the Saab 9-3 in October 2001, at the Frankfurt Motor Show, but in July 2001, it was announced that delays had forced General Motors to postpone the introduction. In September 2002, the hatchback version premièred.
The Vectra C was first seen in November 1999, in a copy of Auto Express. In October 2003, at the Frankfurt Motor Show, the estate version premièred, which had a slightly longer wheelbase than the hatchback and sedan versions. Sharing the 2,830 millimetres (111 in) wheelbase of the estate, an "executive hatchback" sold under the Opel/Vauxhall Signum nameplate. The Signum, which was based partly on the Vectra C, featured a completely different layout in the rear.
The engine range was substantially modified to account for the increased curb weight of the Vectra C. The 90 kW (121 hp) 1.8 litre Family 1 Ecotec engine was reserved for the base model, with the main petrol engine for the Vectra C, making up the vast bulk of production, being the Ecotec 2.2 litre chain driven unit producing 108 Kw (145 bhp); along with a new range topping 3.2 litre 54-Degree V6, with 155 kW (208 hp). In 2003 a 2.0 litre turbocharged Ecotec engine with 129 kW (173 hp) was also notionally offered but was only produced in tiny numbers, rather it being a main engine for another GM brand, Saab. The 2.2 litre was upgraded in 2004 with the 'Direct' name added to the model line indicating the new high pressure direct injection update that increased power output to 115Kw (152 BHP) with improved emissions.
Diesel power, which had become important for commercial success in Europe, is provided by an Isuzu-sourced 3.0 litre DMAX V6 outputting 132 kW (177 hp).
In October 2004, the four-cylinder diesel engine was replaced with a Fiat-designed 1.9 litre Ecotec CDTI engine capable of producing 89 kW (119 hp) in 8v form and 110 kW (148 hp) in 16v form. Handling was reported to be much better than the previous Vectra, but reviews still criticise the overlight feel of the steering, fussy one touch indicator switches, and the ungainly styling of the sedan version.
The Vectra C received a facelift in September 2005, with the début at the Frankfurt Motor Show, and it retained a similar line of engines. However, the power of the 3.0 diesel was increased to 137 kW (184 hp), and the petrol 3.2 litre V6 engine was replaced by an Australian-built turbocharged 2.8 litre High Feature V6 unit. This Saab co-developed motor could produce 170 kW (228 hp). Opel installed the twin scroll turbo engine in its Signum productline with 185 kW (248 hp) output.
The 185 kW (248 hp) version was available for the Vectra later in 2006. Opel also introduced - for the first time - an OPC version of the Vectra, using the VXR name in the United Kingdom. These high-performance variants were only available as hatchbacks and station wagons. In the United Kingdom the power of the High Feature V6 engine was increased to 188 kW (252 hp), giving a maximum speed approaching 250 km/h (155 mph). In Australia and New Zealand, the Holden Vectra ZC series was only available as a saloon and hatchback - Holden did not offer the Vectra C estate due to the presence of the Astra and later Holden Viva (Daewoo Lacetti) estates. The Vectra was dropped and replaced by the Holden Epica, a badge-engineered Daewoo Tosca early in 2007.
Due to stockpiling of 2005 model Vectras for the Australasian market, there was enough supply of the car for deliveries to last through to 2007. As a result, facelifted Vectra Cs were not sold in those markets. In 2008, Vectra OPC was available with either 6 speed manual or 6 speed automatic transmission (Previous Vectra OPC had manual gearbox only). The 2.8L DOHC V6 turbo engine could generate 206 kW (276 hp).
Sales of the Vectra C in the United Kingdom were not as strong as those of its predecessors. For much of its production life, the original Vectra was the fourth best selling car in the country, but the Vectra C never came higher than tenth in the country's car sales charts, though within its own market-sector it held on to second place, behind the Ford Mondeo. In 2007, it finally made the top 10 of Britain's car sales charts, being the nation's tenth most popular new car with over 50,000 sales, outselling the Ford Mondeo for the first time since 1999.
Also, in January 2007, the station wagon variant was awarded Estate Car of the Year 2007, by What Car? magazine. While the Vectra C has been sold in Mexico and Chile as the Chevrolet Vectra, it is not marketed in Brazil, where Chevrolet opted to sell the Astra H under the Vectra brand from 2006 to 2011. Both local-spec cars are powered by the FlexPower SOHC engine originally introduced in 1982 in the Chevrolet Monza.