Location – The Borders, Scotland.

If you fancy a little fly fishing in Scotland’s famed River Tweed, there’s absolutely no need to buy a boat, or stand foolishly in the icy water, just get yourself a Land Rover Discovery 4 and a couple of hand nets, and you’re in with a better than average shot.

I’m not kidding, we’re currently driving across the River Tweed and water is swirling around the door handles and the Disco 4, isn’t batting an eyelid.

Better still, my co-driver is using the Surround Camera system as a live action fish finder, and it seems we’ve got one although, not sure if it’s a local brown trout.

This is certainly the deepest I’ve ever been in a four-wheel drive, and never across a river, that’s running this fast. We can actually feel the weight of the water pushing against the Discovery but, once again, there is no sign of wheel slip or even the slightest loss of grip.

I’m tempted to go even deeper, beyond the 700 millimetres wading depth, but frankly, I reckon we’ve already submerged beyond those specifications.

That’s a good thing to, as we’re told this is the easy part of the off road course, and expect it to get a lot rougher and deeper when we hit the narrow channels, near the famed Floors Castle, in Roxburghshire.

Good thing then, that the engineers back at Land Rover HQ in the UK chose to water proof the belt drives, alternator, air conditioning compressor, power steering pump and starter motor, but again, we have no idea what lies ahead of us today.

Nonetheless, the door seals must be remarkably robust to withstand the speed and volume of water up against the Disco 4 at the moment.

The Scottish Borders region in the Eastern part of the Southern Uplands of Scotland is simply breathtaking, with its Lochs and surrounding grassy hills, which seem more like small mountains to me.

It’s hard to imagine, but this beautiful part of the world was once a brutal battlefield and we’re close to where King James of Scotland was killed in 1460.

While the roads around here are mostly quiet and secluded, there are hundreds of blind corners, which in some cases require super sharp reflexes, and a short dab of your horn on approach, is always a smart move.

The new larger four-piston brake system developed from that on the Range Rover Sport, is exactly what you need to avoid a catastrophe with the local sheep population in these parts, as beautiful as these creatures are.

The quick corners don’t seem to be a problem either, despite the Discovery’s considerable weight. I’m treating the Disco as I would the Range Rover Sport on these narrow twisty roads, and its well behaved with surprisingly little body roll.

The steering is also nicely weighted with good feedback through the steering wheel.

There’s an understeer control system watching over my steering inputs, so if it senses a violent movement of the steering wheel, it will automatically brake the car to reduce speed through a corner.

This is truly a magic place to test the tarmac and handling capabilities of the new TDV6 3.0 Discovery 4, and what a treat this new diesel engine is.

OK, when you hit the Stop/Start button you can tell it’s a diesel, just. But the instant you punch the throttle; you won’t have a clue whether you’re driving a petrol or diesel powered Discovery.

I actually found myself staring at the rev counter to work out what engine was under the bonnet; such is the refinement of this 3.0-litre diesel.

Jointly developed with a combined Jaguar Land Rover team, they have been careful to design unique characteristics for each of these prestige brands, but high torque and a fast throttle response was a requirement for both vehicles.

A major part of this new found refinement is the smooth shifting 6-speed automatic ZF transmission, which seems considerably quicker than the model it replaces.

As I bury the throttle from the merging lane, as we headed southeast out of Edinburgh towards The Borders, you can feel all of the 500Nm,  on tap within 500 milliseconds, which then increases to 600Nm moments later.

Suffice to say, merging into fast moving traffic isn’t an issue with the new TDV6 moreover, so called turbo lag has been completely and utterly dialled out of this powertrain.

While it might be based on the existing 2.7-litre TDV6 engine, the new 3.0-litre diesel is a huge step up; with its unique twin parallel sequential turbochargers providing significantly more grunt across the entire rev range.

But as you would expect, it’s not quite the same design specs as the Jaguar version, with careful consideration going to Land Rover’s penchant for extreme angles in off road situations.

The sump, for example, is deeper than the Jaguar, and the oil scavenge system for the turbochargers has been modified so that no oil collects in the turbochargers while you’re crossing a horribly deformed bridge, as we are about to attempt here in the Roxburghe Estate.

My heart rate has jumped 50 beats or more, but the tension is largely unwarranted; the Discovery makes the crossing without a flinch and with complete poise.

The Discovery feels no different to yesterday’s adventures in the Range Rover Supercharged. It doesn’t seem to matter what they dish up in this off-road minefield, we might as well be driving down George Street in Sydney, as its no more challenging to these vehicles.

But it’s the overall quietness and ride quality of the new Discovery 4, that impresses me most; this is more like a Range Rover than what we have previously been accustomed to in the Disco range, and it only gets better.

Land Rover bosses have been on-and-on, ad nauseum about the word ‘premium’ ever since we arrived in the UK. Well they keep on playing that tune, and I’ll even play it for them, the Discovery is now officially more Range Rover than Discovery.

I’m not saying the Disco 3 was in any way agricultural from inside the cabin, in fact, I always felt like I had a few dollars when driving one, but this new fit out, is simply without peer for a luxury vehicle, which has so far proven to be unstoppable.

There’s sumptuous leather (not slippery like some treatments) from floor to ceiling and enough metal highlights in and around the switchgear to warrant liberal use of the premium tag.

It’s driver friendly too, you won’t need to call customer service or refer to the owner’s manual, in order to work the climate control system.

You can pretty much access each and every major function, via the touch screen, meaning, Navigation, Phone, Audio/Video, 4 x 4 info, Cameras and Climate Control.

It’s also intuitive and minimises the number of steps needed to get to the information you require.

And what about the exterior styling? It’s still unmistakably Discovery, but similar to its 2010 Range Rover sibling, it now has a slightly softer look, for good reason.

Some female drivers, many of who make up the Discovery owner’s club, given its seven seat capacity, found the LR3 to be too aggressive, particularly around the front grille.

While I had no problem with the outgoing look, as I prefer that tough military front end (that’s a man thing, I guess), I can also appreciate the softer front styling of the Disco 4, as it adds more prestige to the model, as do the LED lights treatment, front and rear.

We’re about to literally drop off an embankment, but my co-driver and I, cannot see a thing, time to activate the 4 X 4 info and at least know where my front wheels are pointing.

This is bloody steep and its straight into a water logged channel, or more like another river.

My fear is we might get down there, but getting out could be an issue, with the 30 centimetres of mud we are sitting on.

We’ve already dialled up Mud & Ruts on the Terrain Response, and hit the low range button in preparation for this drop. Actually, Land Rover have enhanced the system by adding ‘Sand launch control’ which should make it easier when driving away in soft by limiting the amount of wheel slip as you drive off. Rock crawl has been refined too and will now apply low level brake pressure in first or reverse at speeds below 5km/h.

But rather than ride the brake on the drop off; I’m going to allow the Disco 4 to drop off the edge using the new Gradient Release Control, that means no foot on either brake or accelerator, as the Hill Decent Control is automatically maintaining brake pressure even though I’ve taken my foot off the pedal. Brilliant, and it’s safer that way, once you get used to allowing the electronics to take over in these situations.

After driving across the River Tweed, I know water is not an issue with the new Disco, but this is even deeper, and we’re driving upstream with a tonne of mud under us.

I kid you not, it’s like driving up the Amazon, but we’re travelling first class and listening to music from my iPod through one of the world’s best sounding in-car audio systems. It’s positively surreal.

We both agree this is stupidly easy although, both diff locks have now engaged, so there’s no loss of traction as we start to crawl out of the water and onto more mud.

When arrived at an old stone bridge with some steep and very narrow ramps in place, and I’m hoping like hell that we don’t have to traverse these things, due to my fear of heights. But sure enough, up we go.

The whole idea of this exercise is that the angle of approach is so extreme, that the only thing you can see ahead are the clouds, which requires steering by the Surround Camera System.

It works, yes; very well in fact, but all I could think of were the consequences of getting it wrong and toppling over the bridge. I prefer my four wheels to be on Terra firma, thanks very much.

While you can have a lot of fun in the 5.0-litre naturally aspirated version with its 276kW and 510 Nm of torque, my pick has to be the new 3.0-litre TDV6, for it’s all round performance and significantly greener output.

Remarkably, the Discovery 4 has been riding on stock standard Goodyear road tyres throughout this entire off road test. You be the judge.

Expect a First steer of the 2010 Range Rover Sport 5.0-litre Supercharged on CarAdvice next week, from Scotland.