The debate around whether the modern world needs motor shows is under the spotlight this week in Paris, with Bentley, Ford, Lamborghini, Mazda and Volvo among the big names who would traditionally have pitched up electing to give the whole jamboree a miss.

The theory goes that motor shows no longer deliver bang for buck; why fight for airtime for your product with 27 other car makers when you can get more coverage and more eyeballs for a (cheaper) digital reveal away from the melee?

Read about this year's Paris motor show here

On the eve of Paris, the motor show cause has been delivered another blow - albeit from the head of one of the car making conglomerates that is actually there. Having skipped last year's Frankfurt motor show while he negotiated with the workers' unions in the States, Fiat Chrysler CEO Sergio Marchionne, has cried off at the last moment again.

No reason has been given, but you'd have thought he'd do everything he can to rock up at an event where almost all of his brands - from Alfa to Fiat to Ferrari to Jeep - have something significant to say. More's the pity, too, because we had an hour of his time scheduled in, and there are few freer talkers than Marchionne when he builds up a head of steam. His views on revitalising Alfa would have been especially interesting, given the recent, positive tests of the new Giulia.

Still, the show must and will go on without him. There may be a very good reason for his absence, but there's no question in my mind that it will cost his brands a share of the spotlight and steal another fraction of lustre from the Paris motor show overall.

Keep up with all the latest Paris motor show news, with all the latest reveals and details here