You probably don't know Alan Phillips. I don't and I'm glad for it, for here is a man of quite maniac zeal, a man who worships at the grail of fuel consumption. Seated comfortably behind the wheel of a Toyota Avensis 2.0-litre D-4D diesel, this eccentric chap completed the 839 mile journey between John O' Groats and Land's End on 50 litres of fuel, averaging an almost unbelievable 75mpg. To be fair to Mr Phillips, his quest did raise a lot of money for the Children In Need charity, but nonetheless it's an arcane task that involves some esoteric driving techniques. You or I are more likely to see something like 48mpg.

This figure is still something many of us would associate with a supermini or citycar rather than a hefty medium-range family saloon like the Avensis. Doors that thunk shut like bank vaults and interiors that feature more airbags than you could count on one hand don't normally record class-leading fuel consumption figures but the Avensis D-4D seems to defy the laws of physics. How can a car return fuel figures more akin to a Smart car and at the same time be built so tough that it can attain the highest EuroNCAP safety score to date, racking up some 34 points and a maximum five-star rating? Only Toyota's engineers can answer that one.

The Avensis D-4D range encompasses saloon, liftback and 'Tourer' estate versions and opens at £15,545. Three D-4D variants are offered, a smaller 2.0-litre 124bhp '130' unit, a 148bhp 2.2-litre '150' option ands a 177bhp 'T180' range-topper. The 2.0-litre powerplant delivers a decent slug of torque - 300Nm to be precise - and performance is reasonable, the Avensis hitting 60mph in 10.3 seconds before running on to a top speed of 124mph. The 2.2-litre D-4D is more advanced as well as being more powerful. It pumps out 310Nm in '150' guise, delivers a 9.3s 0-60mph time and can hit a top speed of 130mph. It's a second generation common-rail diesel which means improvements have been made to the combustion process which produce greater refinement and efficiency even than the first generation common-rail units. Fuel economy for this larger powerplant is almost identical to that of the 2.0-litre option.

Emissions figures of between 146 and 161g/km for all three D-4D engines are backed up by the added bonus of Euro4 emissions compliance (which knocks 3 per cent off benefit in kind taxation) meaning that the Avensis D-4D models are bound to be popular with fleet managers. Whole life costs are admirably low due to a combination of low insurance ratings, reduced servicing time, competitive parts pricing and sturdy residual values. In fact, Toyota reckon that some 60 per cent of all Avensis sales will go to fleet customers.

"The fuel economy figures are something many of us would associate with a supermini or citycar rather than a hefty medium-range family saloon like the Avensis"

Trim levels depend on your choice between five options: Colour Collection, T2, TR, T Spirit and T180. All come with air conditioning, an alarm immobiliser, power windows and mirrors and ABS. The plushest TR, T Spirit and T180 levels also include a colour screen satellite navigation system.

Safety has been prioritised with all models getting no fewer than nine airbags as standard, including a driver knee airbag. Secreted beneath the steering column, this system protects the driver's knees and lower legs from injury. Step from an old Avensis into the cabin of the current car and you'll spot no significant family resemblance. The doors thunk shut like a Lexus and it was to their luxury division that Toyota looked to imbue the Avensis interior with a genuinely upmarket feel. It seems to have worked. Soft touch plastics, neat metallic finishes and a huge cabin make the Avensis feel a class up.

Better sound insulation has reduced weight and decreased noise, but to give some illustration as to how seriously Toyota took refinement, they didn't choose the most refined car in the class - let's say the Vauxhall Vectra - as a comparison. Instead they chose the Lexus LS430 as a benchmark and claim that even at 124mph, there is zero wind noise from the door mirrors. The Mondeo and the Peugeot 407 were identified as class leaders in the area of steering feel, handling and ride and Toyota have tuned the steering for better feedback. The compact strut front suspension is similar to that of the Corolla, but the rear is a modified version of the Celica's multilink system. One advantage of this is that it reduces intrusion into the luggage bay, the saloon version featuring a 520-litre boot.

Even Toyota anoraks may have trouble recognising the latest facelifted Avensis from its post-2003 predecessor but peer closely at the revised front and rear ends and improvements begin to become apparent. The engineers have also been hard at work on improving the suspension and steering systems used across the range, improving the ride (which didn't need much enhancement) and the handling (which really did). Otherwise, it's pretty much as you were.

The Toyota Avensis D-4D may be understated but it has a great deal going for it. It feels reassuringly solid and the diesel engines have some spirit to them as well as the predictably excellent fuel economy and emissions showing. Although the car scores well on almost every conceivable objective measure, it still lacks the bold styling or edgy personality of some of its more high profile rivals. Still, those who choose to overlook the Avensis D-4D line up may be missing out on the most well rounded contender in this corner of the market. More well rounded even than Alan Phillips? We'll leave that up to you to decide.