The Espace is an institution that's been around for nearly a quarter of a century. Only the Plymouth/Chrysler Voyager beat Renault in offering the world’s first MPV - and both models are still in the price lists. However, compare an early Espace with the current offering and you'll see just how far the breed has come in two decades or so.Now in its fourth iteration, the current Espace was launched five years ago, so it's getting rather long in the tooth. If you're wondering why we're only now testing it, it's because the big news is the availability of the fabulous 175bhp two-litre turbo diesel engine, already seen in the Laguna.No doubt you're already getting short of breath with anticipation, and you'd be quite right to, because the new powerplant makes a great MPV even better. Introduced in 2006, this edition of the 2.0 dCi powerplant is impressive. Not only is it virtually as powerful as the three-litre V6 turbo diesel also available in the Espace, but it uses around 25% less fuel.As a result, its CO2 emissions are significantly lower while it's also quicker in terms of both acceleration and top speed. It seems that Renault has mastered the automotive equivalent of turning water into wine.Press the starter button and it's obvious there isn't a petrol engine in the nose. But it soon settles down to a smooth idle, only getting clattery as you explore the upper reaches of the rev range. It's not too intrusive, though, things being helped by focusing on the 266lb/ft of torque on offer.The six-speed manual gearbox offers smooth changes, but it's a shame there's no automatic option for this powerplant; if you don't like swapping ratios yourself you'll have to settle for the 140bhp version of this engine and a lower state of trim.Six of us took the Espace over to Austria and back, covering over 2000 miles in a week. Virtually all those miles were done in a non-stop journey there and another one back, so you're unlikely to ask any more of your own Espace if you were to buy one.Crucially, though, it was the long-wheelbase Grand Espace that we borrowed; opt for one that's less Grand (a standard Espace in fact) and you'll probably find it too cramped to travel six-up for any great distance, especially if you want to carry any luggage.Despite its advanced years, the Espace is a true luxury express. The interior is spacious and well-finished, while there are the usual three million different seat configurations for ultimate flexibility. Our test car also came with a glass roof, complete with electric sun blind. At £1250 it's a costly option, but it transforms the interior of the car and is good value compared with a typical car-sized sunroof.It's not all good news, though; it can't be too long before the fifth-generation Espace is released, and when it does arrive there are a few niggles to be sorted. The wing mirrors are too small, while the stereo in my dad's 1978 Morris Marina sounded better. The interior layout is flexible, but the seats aren't handed so the catches are in the wrong place on the driver's side.Then there's the electric driver's seat adjustment; switch the engine off and the seat scuttles back and down to help you get out. But when you climb back in and fire up, the seat doesn't return - which is a real pain if you like it forward and up, as I do.Another thing that needs attention is the suspension set-up. When combined with the 18" wheels and low-profile tyres of our car, the ride is firmer than it should be – after all, this isn't a sports car. Considering the wheels cost an extra £1000, you'd be better off keeping the standard 17" items and putting the money towards a stereo upgrade or a DVD system to keep the kids happy.One thing that doesn't need to be changed is the superb visibility; the Espace's windscreen pillars are amazingly thin for such a modern car. With a trend towards ever-thicker pillars, it can be assumed that every fresh generation of car will have thicker, more intrusive pillars than before – so let's hope Renault doesn't fall into the same trap when the next-generation Espace appears.The Espace is a an excellent MPV, let down by a few niggles – something to be expected with the car so long into its life cycle. It's the issue of value for money that's the hardest to resolve; in standard form this range-topping 2.0 dCi costs a hefty £33,275. Our test car cost an extra £4050, taking the total bill up to a very steep (and sobering) £37,325, which is a lot of dosh for a car that doesn't wear a premium badge. Engine 1995 cc, 4 cylinders Power 175 bhp @3750 rpm Torque 266 ib/ft @1750 rpm Transmission 6 speed manual Fuel/CO2 37.2 mpg / 200 g/km Acceleration 0-62mph: 10sec Top speed 127 mph Price From £34342.00 approx Release date 23/03/2006