OPEN the tailgate of this Mondeo estate and you may think there's someone hiding under the loadspace floor as the carpet takes an upward sweep where you expect it to stay flat.

But no, this space invader hides the extra battery that turns the Mondeo into a hybrid vehicle, mixing an electric motor with a petrol engine to the benefit of a business user's tax bill.

The reduced CO2 from the tailpipe also does its modest best to save the planet even if it means less space for your travelling clutter in the boot and, crucially, a driving experience you'll either accept as part of turning greener - or not.

You can't plug your Mondeo hybrid into the mains, it recharges the battery when you lift off the gas and uses the salvaged electricity to either power the car along in silence at low speed or help out the petrol engine when you need maximum overtaking urge.

After a solid 800 miles of testing roads the result was a dash readout of 47.9mpg. That's a very decent return for a big car with a petrol engine doing most of the work; except that you'd do better still with (whisper it) a diesel under the bonnet.

Yes, the diesel's higher CO2 reading means more tax for the business user but there's considerable compensation with a car that costs almost the same and goes with much more urgency when poked with a sharp stick.

The hybrid is not a car for the press-on driver; it's gearbox sending engine revs rocketing if you're in a hurry.

Which is a pity because there's enough enthusiasm for corners to make you wish it went as well on the straight bits.

Ford launched its hybrid in the poshest versions of the Mondeo but has now brought the entry level down a bit, but this ST-Line model still tops £30,000 before you add any extras - the test car's £36,325 bottom line formed from ticking boxes marked with names like Stealth (smart grey paint) for £600, glass sunroof (£1,200) and fuller leather trim and heated rear seats for £750.

Standard kit is actually pretty generous, with 19in alloy wheels, powered and heated front seats, cruise control, Ford DAB radio and satellite navigation and part leather trim.

Those big alloys look the business but don't help the ride, already toughened in this ST-Line with sports tuned suspension to the extent that pockmarked city streets are not this car's natural hunting ground.

Other nods to a sporty life include alloy foot pedals, red stitching on steering wheel, door trims and centre console and a rear spoiler, unique to the estate version.

The Mondeo is a big car, wide enough to make tighter multi-storey car park entries a bit of a nerve jangler. The upside is bags of space for people inside, even if the hybrid's battery makes demands on the boot.