The G-Class, or as it's more commonly known, the G-Wagen, is a car for rappers. Of course, you don't have to be a rapper to buy one, but you need to have their money and desire to move quite a large entourage around in absolute luxury and comfort. It is, without doubt, one of the most remarkable cars we've ever driven.It also has more in common with a boat, than it does with a car. From the first moment you get in it, you can't quite believe what's happening. We remarked out loud, to no one in particular: "What on earth am I driving?" That's because it looks like a car, has the usual number of wheels and such, but drives like a boat. It also stops like a boat. Slowly. Very slowly. But we can forgive its slow stopping speed, because it's enormous and very, very heavy. It weighs two and half metric tonnes. To give some context, the new Range Rover is half a tonne less.But when you start to understand that the car drives like it's on the sea, you start to worry less about it and learn to drive it with that in mind. The steering though, does need to be watched, as it's not even vaguely sensitive and you need to manhandle it around roundabouts and corners or you'll just go over them. Not that going over things is much of a problem in the G350, because it feels like you could drive it over a house and not feel much in the luxurious cabin.In the car we drove, that interior was incredible. Leather everywhere, a massive, luxurious sunroof that has a sunshade to give you darkness during the day - keeping you cooler, in hot climates - or brilliant access to the elements if you need cooling down. There's a massive tablet-style navigation and car management screen. It's clear and easy to read, and acts as a reversing camera screen when you back up. We promise you'll need this, as the spare wheel obstructs what you can see out of the back. That said, it's a flat back, so you don't need to think much about bits that you can't see that might stick out.The one thing that puzzled us was the inclusion of flappy-paddle gear changers. The car does a good enough job in automatic mode, and this isn't really the sort of car you can wring a lot of performance out of by shifting manually. It's far better to just let the automatic box do its thing. You can select one of three modes, manual, economy and sport. Economy and sport both felt pretty similar here, although there's the obvious lingering in gears with the sport mode.Performance is an odd thing too. The car can, apparently, get to 62mph in 9ish seconds. And when you put your foot down, it definitely makes the right sort of noises, and you can feel it tug, but it never feels especially quick. Perhaps that's part of its skill, it's just effortless. It's worth pointing out though, that the AMG version of this car can get to 62 in 5.4 seconds, which is madness. It's like a boat still, but someone has strapped a jet engine to the back of it.The G-Class is a proper off-roader too. There's a low-range mode, as you'd hope, and three different diff-lock modes - front, rear and centre. You can put the car into low range while you're driving \u00a0and the four-wheel drive is permanent, which gives you a lot of grip on the road.\u00a0When it comes to running costs, you should prepare yourself for the worst. By our calculation it will cost at least \u00a3134 to fill up the G350 at the pump, and Mercedes says you'll see a maximum of 28mpg. We suspect, in real world driving on British roads you'll get a lot less than that. Oh, and if the day-to-day costs weren't enough, there's also the \u00a31,000 a year you'll need to find to tax it. But then, anyone who can drop a hundred grand on a car like this can probably afford the running costs.If you can afford the \u00a397,000 for this car, as tested - the starting price is about \u00a383,000 - then why not just spend twice as much and get the AMG version? That's certainly no more expensive to tax, although running it might be a bit more costly. Either way, the G-Class is ace, it's an environmental disaster from a fuel economy point-of-view, but it's a lovely place to sit and it's built with both luxury and indestructibility at its heart.