A PHENOMENAL petrol engine has been developed by Mazda that mimics the characteristics of a diesel with excellent fuel economy.

The SkyActiv-X engine is making its debut in the latest Mazda3 hatchback and will be on sale later in the year priced from around £26,000.

With either automatic or manual transmissions it impresses in every way and the manual version can deliver some amazing fuel figures.

On our drive we saw an average of 63 miles per gallon but driven purely for economy it managed to hold an exceptional 157mpg for almost five miles.

Officially it is rated at 51 to the gallon with emissions of 125g/km and that's under the new WLTP fuel testing regime and on 16-inch wheels.

Under the old NEDC system the SkyActiv-X looks even more impressive where its official return is 64mpg.

It is a 2.0-litre supercharged engine with 180ps on tap but its magic comes from compression ignition similar to a diesel.

The engine switches automatically from spark ignition to compression mode and on the road it feels utterly conventional.

Its operation - and efficiency - can be monitored from the Mazda3's main display screen and that helps on the fuel saving front.

Mazda started work on the so-called Spark Controlled Compression Ignition (SPCCI) system back in 2013 on a mission to create the ideal combustion engine.

On paper its performance figures outrun the standard 2.0-litre Mazda3 by some margin with a 0 to 60 acceleration time of 8.5 seconds compared to 10.4 and a top speed of 133mph as opposed to 122mph.

Automatics and all-wheel-drive versions will also be available and while those are slightly less economical - 46mpg for the auto and 47 for the AWD - and on the road the SkyActiv-X feels noticeably livelier.

A clever electronics system which includes an effective stop/start set up and a 24-volt mild hybrid arrangement are other eco aids as is rev matching when changing gear.

The overall result is a very smooth drive and the engine is free revving with much more mid-ragne torque, although fifth and sixth gears are really best only when cruising.

When it arrives in September the new engine will join the SkyActiv-G petrol and SkyActiv-D diesel versions of the latest Mazda3 which was launched earlier in the year priced from £20,595.

The SkyActiv-X engine will be available in all trim levels and the cars we tried were also fitted with head-up displays which not only give information about the vehicle's speed but also shows navigation instructions.

The SPCCI system is a ground-breaking achievement for Mazda and no other car company has similar technology. Moreover, it has been designed to be scalable and could be used in smaller - and larger - capacity blocks.

Mazda claims the SkyActiv-X engine is some 20 per cent more fuel efficient than its regular petrol engine and has up to 30 per cent more torque and with a compression ratio of 16.3:1 it is almost off the scale in comparison to other engines.

Certainly it is the best version of the Mazda3 and really does off the best of both worlds for private and company car users alike.