For more than 15 years, BMW has used basically the same recipe for its class-leading X5 SUV.

Pretty much the same body shape, along with much the same three-litre, six-cylinder petrol or diesel engine (among others) – and a roughly unchanged drivetrain.

You might think they’d eventually run out of ways to make that same old recipe exciting or appetising.

Yet the latest X5 – the third generation of this iconic model – is just as fresh and exciting as the day it was first unveiled to an unsuspecting motoring market back in 1999 (yes, last century) – even though it hasn’t changed all that much.

Along the way there have been some changes, of course. A variety of engines plus all manner of technical and technological changes. Even M-Sport models with massive power and performance.

But this latest X5 is instantly recognisable as the progeny of those to have gone before. You still see the original X5 models in every city and town – and they still look as contemporary and attractive as ever.

It’s timeless piece of styling. Compare the original X5 to the original ML-Class Mercedes – and stand both beside their current models – and you’ll see what I mean.

The X5’s crisp lines remain. The straight-six-cylinder configuration is still the staple power source – although there’s now also a smaller, entry-level diesel and some thumping V8 and performance diesel variants.

But somehow, while retaining the same ingredients, BMW’s clever bunch of engineers have managed to make this latest X5 feel like a noticeable step forward. It’s evolution, rather than a revolution – and to be honest it’s not easy to put your finger on the reason it feels substantially better than the model it replaces. Even BMW’s marketing department could only come up with “Simply better”. But that sums it up.

For our week-long test in the X5, we drove the familiar 3-litre turbo-diesel variant, known as the xDrive30d. It’s more powerful and more fuel-efficient but not massively more expensive.

It sits relatively low on the X5 model list – the third-cheapest, just above the new, four-cylinder models and just sneaking in under the $100-grand barrier. Other more powerful variants range from the sDrive35i ($107k), through the twin-turbo V8 xDrive50i ($133,900) right up to the freakish M50d (3-litre turbo-diesel with three turbochargers, 280kW and 740Nm) at $147,900.

Tempting as those models are, the xDrive30d has roundly been acknowledged as the value buy in the X5 range and we couldn’t disagree.

The twin-turbo diesel produces a respectable 190kW in its new guise (10kW more than before) and a brawny 560Nm – delivering a linear and substantial stream of power that gets this big machine up and galloping with no hint of effort. The engine is smooth and quiet but surprisingly responsive for a diesel, with a reassuring low-down thrust.

The fact it will reach the speed limit in a brisk 6.9 seconds, while still sipping a staggeringly-low 6.2L/100km, is testament to the ever-evolving appeal and efficiency of diesel technology.

Helping achieve that frugal thirst – and putting that power so smoothly to the ground – is BMW’s latest eight-speed auto transmission – seamless and intuitive and giving the X5 massively long legs on the open road.

An auto stop-start system also helps save fuel in heavy traffic conditions.

BMW says the X5 is considerably more aerodynamic thanks to “air curtains” which redirect airflow around the wheel-arches to reduce drag, supplemented by the new breather vents just behind the front wheels.

Specification levels on our test machine were also impressive.

BMW boasts that this model represents much-improved value on the previous model, with standard kit including 19-inch alloys, bi-Xenon headlights with LED fog lights and high-beam assist.

Driving aids include BMW’s clever head-up display plus a suite of technology called Driver Assistant, comprising lane departure warning, frontal collision warning, pedestrian warning, a city-traffic auto braking function plus rear-view camera and 360-degree parking system.

Electric windows, mirrors and front seats, plus an electric rear tailgate, highlight the convenience package, along with the now-familiar iDrive cabin control system with internet functionality and premium audio system with Bluetooth connectivity and audio streaming.

Cabin ambience in the new X5 steps up a level from the previous model – it feels airy and modern with judicious use of high-quality finishes such as stitched leather and polished timber.

Ride quality is also notable.

While higher-end models offer added performance plus some extra kit, the xDrive30d strikes a great balance of price, performance and packaging.

For those looking lower down the scale, though, the new X5 range will offer, for the first time, a four-cylinder turbo-diesel variant in the xDrive25d and, also for the first time, a two-wheel-drive only variant, the sDrive25d. As well as a thirst as low as 5.8L/100km, these two models drag the entry-level price for an X5 down to a juicy $82,500, plus onroads.

While power and performance are more modest, it’s still an attractive way to get an iconic SUV into your driveway.

Having your cake and eating it, if you like.

Sounds like a diet we could all get used to.

BMW X5 xDRIVE30d

DETAILS: Five-door, five or seven-seat premium SUV with six-cylinder turbo-diesel engine and eight-speed automatic transmission.

TECH STUFF: 3-litre, in-line six-cylinder twin-turbo diesel engine with common rail direct injection produces 190kW@4000rpm, 560Nm@1500-3000rpm; eight-speed automatic transmission with steptronic manual function; permanent all-wheel-drive.

FEATURES: Driver and passenger front, side and head airbags; dynamic stability control with dynamic traction control, cornering brake control and dynamic brake control; biXenon headlights with high-beam assist; head-up display, blind-spot and frontal collision warning systems; electric seats, mirrors, windows and rear tailgate; 19-inch alloy wheels, leather trim, satellite navigation, Bluetooth connectivity; auto stop-start system.

THIRST: 6.2L/100KM (official combined figure).

PERFORMANCE: 0-100 km/h in 6.9 seconds.

VERDICT: Same recipe, but still the pace-setter in this category.

BOTTOM LINE: $99,900 (plus onroad costs).