THE BMW ESTATE car is not a pioneer. When the first model arrived in the ’80s, we’d already seen Mercedes estates, and watched the Griswold family trek to Walley World in a station wagon. But in today’s era of forensic product planning, its genesis now seems pleasingly spontaneous and unpretentious.

It started when BMW employee Max Reisbock converted a 3-series saloon into an estate in a friend’s garage, just so he’d have more space to go on holiday with his family. Reisbock never expected his BMW bosses to be so impressed that a near-identical 3-series Touring would make production by 1987. Or that the 3-series Touring would prove so popular that a 5-series Touring would arrive four years later. He just wanted to cram an unreasonably large amount of stuff in the back to stop the endless whining. Today, despite the crossovers and SUVs and MPVs, many of us still want the same thing: a BMW saloon with an extra bit on the back. Around 25% of the 20,000 5-series sold in the UK each year have a tailgate. Now there’s a new one, the fifth-generation G31.

It grows in every way compared with its predecessor, at 36mm longer, 8mm wider and 10mm taller. Despite this increase, the Touring is also around 100kg lighter than before, a new steel and aluminium body accounting for 70kg of that reduction: the bonnet, front wings, doors, roof and tailgate are all aluminium.

Naturally, a new Touring has to be more practical too. With the rear seats in place, you’ll get an extra 10 litres of stuff in the boot. Its 570 litres compares with 640 litres for the Mercedes E-Class, and 565 litres for the Audi A6 Avant. The rear seats split 40/20/40 and can be dropped with a press of some buttons that are easily accessible in the boot, at which point luggage capacity swells to 1700 litres (E-Class: 1820 litres; A6 Avant: 1680 litres). Relatively small increases, perhaps, but they can be heavier litres: self-levelling rear air suspension is standard, taking a maximum payload of 730kg, up 120kg. You can also tow up to two tonnes.

In line with boxy BMW tradition since that first E34 5-series Touring, the rear window independently opens, so you can drop in lighter items and avoid hoiking up the heavy tailgate, and - a more modern touch - the tailgate is electrically powered as an option, meaning its weight is of no consequence anyway.

However you access that storage space, the load cover automatically retracts and then lowers again like a magician revealing and concealing a caged assistant. The contents don’t disappear, but the load cover and the net that extends from the back of the rear seats to the ceiling to cover big loads now can: BMW has created a compartment beneath the boot floor specially for them. So when you drop the rear seats, those bits no longer have to be removed from the car, with the risk of damaging them.

A revised rear axle ensures a lower boot floor, the aperture is wide… you’ll get a lot of kit in the back there. The rest of the interior is lovely, with standard leather, a low-slung and comfortable driving position and a confident horizontal sweep to the dash architecture for a big-car luxury feel; the optional Comfort seats with massage function are sumptuous enough to elicit groaning, and yet entirely legal.

The rear seats have more than generous legroom, and there’s room for three kids’ seats, if only two sets of Isofix anchors, like the saloon. The controls are neatly and logically arranged, and the infotainment system - 8.8-inch touchscreen with sat-nav standard, 10.25 inches optional - is up with the class best, underlining the Touring’s considerable appeal.

Four engines are available at launch, including the 2.0-litre 530i and 3.0-litre 540i, all available in either SE or M Sport trim. We drove the 520d and 530d turbodiesels. The 520d makes 187bhp/295lb ft together with 65.7mpg and 114g/km, enough to tempt 80% of buyers. It offers plenty of low- and midrange flexibility, and delivers sufficient rather than plentiful thrust. Mostly it’s impressively refined for a four-cylinder engine, but it does strain vocally soon after 3000rpm, and downs tools altogether at 4000rpm; the smooth and responsive eight-speed auto easily glosses over that narrow powerband. The price increases from the 520d SE’s £38,385 to £46,235 for the 530d, but consider this: not only do you get 261bhp and 457lb ft, but also 60.1mpg and 124g/ km. That means, company car drivers, that Bene- fit in Kind increases just 4% to 28%. That it has a far more cultured idle, makes smoother progress through the rev range and - the key bit - has a humongous extra wodge of performance that makes it a significantly more satisfying drive. Either way, the 5-series Touring is extremely refined at a cruise. Road- and wind-noise is muted, and on the optional adaptive dampers fitted to both test cars (M Sport cars can now have standard, adaptive, or sports suspension), the ride generally lulls gently, though there is a little extra patter if you upgrade from 18- to 19-inch wheels, if not enough to caution against them. The suspension is a little more comfort-focused than a saloon’s, and there’s some well-contained body roll from a set-up that prioritises comfort over outright dynamics. It probably hits the sweet spot for most drivers: it grips, turns and flows down a tricky road with impressive composure, but it’s just not a particularly involving driver’s car in the way the smaller, more nimble 3-series is. There’s a big gulf between the two.

Steering that’s about as feelsome as an arcade game’s doesn’t help, though the 530d helm felt nicer. The 520d on 18-inch rubber and adaptive suspension felt almost too light in Comfort mode, and while Sport’s extra weight was welcome, an unnatural self-centring sensation persisted. The 530d was identical save for 19-inch alloys, but its suspension is a little firmer to account for the weight of two extra cylinders. Whatever the reason, the 530d felt more positive, weightier and natural too. That’s yet another reason to upgrade to what’s now the most powerful diesel, what with the 535d being canned due to low take-up and the M550d xDrive unlikely to come here.

xDrive all-wheel drive will be optional on the 520d from July, and is optional on the 530d. Previous experience with the saloon tells us it retains a BMW’s rear-biased feel, while subtly adding extra composure in tricky conditions or when accelerating hard from a junction.

However you spec your 5-series, this is one of those rare cars that just soaks up everything you throw at it: epic treks, growing families, massive payloads, it does it all, and I’d own one in a second. If you need more space, you’ll need someone like Reisbock to build you one of those trailers that consists of the back half of a 5-series Touring. A couple of decades since we first saw one, BMW still has no plans to put thatinto production.