What is it? The Ecoflex badge is reserved for Vauxhall's greenest engines. Here we're testing the 162bhp 2.0-litre diesel version in the five-door Astra.
It averages an impressive 62.8mpg, while CO2 emissions of 119g/km mean the Astra attracts just 13% company car tax.
The equivalent Ford Focus, the 2.0 TDCi 163, averages just 56.5mpg, has emissions of 129g/km and an 18% company car tax rating but costs virtually the same as the Ecoflex Astra.
However, the Astra's figures fall short of the VW Golf Bluemotion Technology's economy of 65.7mpg and emissions of 114g/km. The Golf has less power, but it also costs less to buy.
What's it like to drive? The Astra's 2.0-litre diesel engine is strong and flexible. Whether you need pull swiftly out of a junction, or overtake on the motorway without the need to change gear, there's more than enough grunt in reserve.
You hear a bit of rattle from the engine under hard acceleration, but it's no noisier than its rivals', and it won't bother you at 70mph. The standard stop-start system works smoothly, too.
Ride comfort is pretty good, and while there's some body roll in bends, it's not excessive. Only the dull steering stops you having fun when the road gets twisty.
Road noise is always subdued, but the door mirrors generate some wind noise at speed.
What's it like inside? The cabin is much the same as it is in other Astras, which means the steering wheel and seat are easy to adjust, and the dashboard looks quite stylish. However, higher-spec models have lots of buttons, so the dash can be tricky to navigate quickly.
Most plastics look classy, but not all of them feel as dense as you'd expect at this price.
Despite the swooping roofline, there's enough room for taller adults to get comfortable. Legroom is equally abundant, while the 370-litre boot is larger than either of its key rivals'.
Should I buy one? This Astra is a good car; it's decent to drive, there's enough space for all and the emissions and fuel economy are low. However, we can't help thinking that a starting price of almost 23k is too high for an Astra.
The Focus is better equipped, while the Golf is more economical. What's more, both are better to drive and have higher resale values.
What Car? says