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.