Parkers overall rating: 3 out of 5 3.0

Miles per pound (mpp) Miles per pound (mpp)

Reliable fuel consumption data for comparison purposes is not available for this model.

Fuel economy

A more stringent standard for fuel economy (WLTP) was introduced from September 2017, and this model was not required to undergo that test. Its fuel economy measured under the previous test system was 25 - 47 mpg. However these figures are less likely to be achievable in real world driving and so should never be compared to another car's mpg which was measured under the newer, more realistic WLTP system.

Depreciation is the single biggest concern – Signum loses value quickly. This can be minimised by negotiating a healthy discount from a dealer, scouring the car supermarkets for bargain cars or buying a two-year old car. Used buyers don’t have to worry so much – the worst depreciation comes in the first 18 months. The petrol engines are thirsty because of their size, but no worse than similar ones made by other car makers.

The diesels give good fuel economy and – as Signum is based on the Vectra – servicing is good value and intervals are very well spaced (up to 20,000 miles for the petrol; 30,000 for the diesel). The V6 likes a drink but other units are good to very good on economy. Biggest cost is likely to be depreciation – we doubt that there will be a big demand for used models.

Signum is not particularly environmentally friendly. With an average of 195 g/km CO2 across the line-up, its emissions are fairly standard for an executive hatchback. However, it’s worth noting that the line up has a high number of diesel models, bringing the average down and giving buyers more choices of low-emission versions. Diesels typically produce less CO2 than petrol engines with similar power outputs.

The range is not particularly economical, averaging 37 mpg.

Proving robust and reliable. Just a couple of recalls: one to correct a slipping exhaust pipe in August 2004 and another to fix a rear axle hub that may not be to specification.

Ongoing running costs

Road tax (12 months) £220 - £630
See tax rates for all versions
Insurance group 17 - 29
How much is it to insure?