Mazda3 Fastback saloon - MPG, running costs & CO2

The Mazda3 Fastback has an economical engine, but the automatic gearbox is best avoided

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MPG, running costs & CO2 Rating

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The Mazda3 Fastback only comes in 2.0-litre petrol form, which puts it at a disadvantage to the competition when it comes to choice. However, on paper, that single engine is a good one, with claimed economy that beats many smaller, harder-working engines in rival cars thanks to clever new technology.

Mazda3 Fastback MPG & CO2

A 178bhp, 2.0-litre Skyactiv-X petrol is the sole engine option for the Mazda3 Fastback. Thanks to its strong power output, it never feels strained, yet the impressive 52.3mpg fuel consumption still feels possible in normal driving.

The Mazda3 Fastback has a six-speed manual gearbox as standard. You can choose a six-speed automatic but it’s best avoided unless you’ll be spending lots of time in stop-start traffic. It’s a little slower from 0-62mph than the manual gearbox and returns around 5mpg less, so you can expect 47mpg on the 16-inch alloy wheels and 45mpg on the bigger ones. With CO2 emissions of 117g/km, it’s several bands higher for company-car tax, and it costs more to buy than the manual version in the first place.

The manual manages a CO2 emissions figure of between 96-102g/km (depending on the wheel size you choose), which places the Fastback in low brackets for Benefit-in-Kind (BiK) company-car tax.

Insurance group

Choose the Fastback in Sport and Sport Lux and it occupies insurance group 22, while the GT Sport versions are rated one group higher.


The Mazda3 Fastback comes with Mazda's 60,000-mile/three-year transferable warranty. There's a paint and surface corrosion warranty that also lasts for three years, regardless of mileage, and an anti-perforation warranty that lasts 10 years – also regardless of mileage.


The Mazda3 Fastback will need servicing every 12,500 miles, or annually (whichever comes first). Dealers offer substantial savings on servicing costs with pre-paid plans; a three-year service plan costs £800 for the Skyactiv-X engine, and can be paid monthly or in one lump sum upfront.

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