This is not going to be a case of damning with faint praise, but the Touareg V10 Altitude impressed me most of all when it was standing still. I had popped into a service station for some light refreshment, and when I got back to the car I was dismayed to find that the engine wouldn't start, despite my turning the key in the ignition five times.It was only when I happened to glance at the revcounter that I found it actually had fired up at the first attempt - I just hadn't heard it over the noise of traffic doing 40mph on a nearby dual-carriageway. (Fortunately, the Touareg's start motor won't attempt to engage when the engine is running, otherwise I'd have known all about it.)When all the banging and crashing that goes on inside a five-litre, ten-cylinder diesel engine even at idle can be suppressed to this extent, it's clear that automotive technology has reached a very high level. Twenty years ago, nobody could have believed that this would be possible, and it would also have seemed like the working of a deranged mind to imagine that the same engine could haul such a vast object as a Touareg from 0-62mph in 7.4 seconds, or on to a top speed of 143mph.You have to pay a lot for such things. In top-level Altitude form, as tested here, the Touareg V10 costs over £57,000, has a combined fuel economy figure of 22.4mpg and is rated at 333g/km for CO2 emissions. If you buy one of these cars and drive it past a hospital, you can derive some comfort from the fact that you have contributed quite a lot to the expense of running the place through your contributions to HM Treasury.The V10 Altitude comes as standard with several features which are either optional or not available at all on cheaper Touaregs, most notably the self-levelling air suspension which is intended to improve ride quality, off-road ability (approach and departure angles go up from 28 degrees to 33 degrees), towing prowess and ease of connecting or disconnecting a trailer.I can't speak for the towing or off-roading aspects from personal experience, but the air suspension's effect on the Touareg's road manners seems questionable. This isn't a major issue, since the Touareg actually behaves remarkably well on ordinary tarmac compared with most other large SUVs.The problem comes from within, in the sense that two of the Touareg's biggest rivals in terms of ride and handling are the Audi Q7 and the Porsche Cayenne, both of which are built on the same platform (or an extended version of it in the case of the Audi) as the VW. The Cayenne is more obviously sporty - it would hardly be a Porsche otherwise - while the Q7's behaviour is astonishingly graceful for such an enormous vehicle.None of the models in the Cayenne line-up is directly comparable, since there is no diesel version, but the ultimate Q7 is cheaper, more powerful (despite its smaller engine), more spacious, more economical and less CO2-intensive than the Touareg, as well as having a badge that must surely appeal more to buyers operating in the £50k-plus bracket.Still, there's no doubt that the Touareg is an uncommonly luxurious SUV. It's also exceptionally well-equipped, especially after the 2006 makeover which included a minor facelift (making it look slightly more like the Eos coupé-cabriolet) and the introduction of several new or improved features such as ABSplus, which is claimed to reduce stopping distances on loose surfaces by up to 20%.Other enhancements include rain brake support, fading brake support, understeer control logic (a method of electronically controlling any tendency to go straight on when you should be turning a corner) and Active Rollover Protection, which sets off the head and thorax airbags if the system detects that the car is about to fall over.That last one is largely intended for severe off-road situations, though it's the combination of on-road power, refinement and luxury which is more likely to tempt well-funded SUV enthusiasts into a Volkswagen dealership. Engine 4921 cc, 10 cylinders Power 313 bhp @3750 rpm Torque 553 ib/ft @2000 rpm Transmission 6 speed semi-auto Fuel/CO2 22.1 mpg / 333 g/km Acceleration 0-62mph: 7.8sec Top speed 140 mph Price From £58846.00 approx Release date 01/03/2007