It's the sheer size of the Frankfurt Motor Show that everyone always talks about.
There's no getting away from it, the richest and most prolific parts of Europe's new car industry are here in Germany - and if you want to catch every new model launch on the opening day, you can easily walk ten miles up and down the half-mile boulevard that links this mammoth show's dozen exhibition halls.
Audi and Mercedes are at one end of this automotive parade; BMW right at the other, and those of us using shoe-leather to connect them up were confronted with a new hazard this year - the chance of being run down from behind by one of the dozens of completely silent, production-spec BMW i3 electric cars being used as shuttles to convey lazier hacks from one end of the affair to the other.
There's always traffic, mind you, but you can usually hear it coming. Thankfully a pair of cute but leggy Issigonis Minis, shutting with the secondary purpose of publicising a Mini-sponsored party at the end of press day, could be identified 100 yards away by their timing-chain rattle.
Frankfurt's crop of new cars was as huge as ever, and split as ever into three categories - cars and concepts that were really new; new cars that seemed to have been coming a long time; and useful improvements to familiar faces. Jaguar sprang to the head of the "really new" group because its trend-setting C-X17 SUV did so much more than look great: it confirmed that the much-rumoured small car Jag is really coming - on entirely new aluminium underpinnings with 1700 newly hired people to build it. Biggest deal of all, the new range would include an SUV!
Ian Callum's single blue concept car embodied all this, as well as proving that Jaguar's designers have the skills to extend the design values and features freshly revealed on the F-type sports car to an SUV. This thing made a show star for sure.
The "really new" brigade included plenty more SUVs, most of them compact. The remarkable success of the Range Rover Evoque, still booming after three years, is far from lost on the rest - especially Lexus with their LF-NX, a design many thought over-aggressive. Nissan Juke clones continued to pile up, the latest examples being creditable concepts from the likes of the Suzuki iV-4 and Kia Niro.
The only full-size soft-roader - and one of the few Chinese offerings here - was a Porsche Cayenne-sized Chang'an concept that looked considerably better than its exalted rival, even if unlikely to beat it on the road. Audi showed new determination to position its Quattro brand right at the top of the tree with a thoroughly believable Sport Quattro coupe, and a beautiful but much less logical coupe off-roader, the Nanuk.
The "new but coming a long time" brigade reminded us how the European industry has used the various phases of new car creation to carry it through tough times (which on the mainland are only just starting to abate).
The real Porsche 918 Spyder was revealed at last, the BMW 4-series was present in all its much-anticipated glory, and that manufacturer's i3 and i8 electric offerings also showed up in near-production guise. Honda's NSX was there again, and Ford attempted to heal over an gap of several years between showing us its new Mondeo and offering it in a European showroom by displaying a heavily decorated Vignale version. Vignale, it seems, is to be the new Ghia.
Much of the rest was business as usual for Frankfurt. Three fast sedans - Honda Civic Type R, Peugeot 308R and Subaru WRX - bobbed up to challenge Renaultsport's creations. Lots more received facelifts: the Renault Megane, the Peugeot 3008, the Skoda Yeti, the Chevy Camaro the Dacia Duster and the Audi A8 and a dozen more.
Overall, the heartbeat seemed to have returned more or less to normal. Here was the motor industry, now well into recovery from a bad illness, doing okay. Finding all this out may have been hard on reporters' feet, but it was a gratifying sight.
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