New Opel Monza Concept at Frankfurt 2013 signals a new big coupe from Vauxhall

A new Opel Monza Coupe will arrive at the Frankfurt Motor Show in September, previewing a new big coupe from Opel and Vauxhall.

There was a time, for those not old enough to remember, when mainstream car makers produced big saloons and coupes. But no more.

With very few (low-selling) exceptions, car makers like Vauxhall and Ford have given up their full-sized saloons and downsized, with SUVs of varying sizes now seen as the real future.

But according to Auto Bild, Opel (and therefore, we assume, Vauxhall) are planning a return to making cars they think will sell against competition from the Premium Brands, with the return of the Opel Monza.

The Monza was a big coupe from the 1980s (sold as the Vauxhall Royale Coupe and the Opel Monza in the UK) and it looks like Opel/Vauxhall are planning a modern equivalent, although we’re not too sure just how big it will be.

Auto Bild do say it will be a four-seat, rear-wheel drive coupe, which rules out using any current European platform. So that leaves probably two choices for the underpinnings – Cadillac or Holden.

It is just conceivable that GM could take the Holden we know as the Vauxhall VXR8, turn it in to a coupe and stick a Monza badge on.

Probably more likely is a Cadillac platform, either a Monza based on the Cadillac ATS (which is 3-Series in size) or, perhaps, a Cadillac CTS Coupe with a European look.

If Opel/Vauxhall are going the Monza route for production, it’s hard to see a case for an ATS-based car which would be similar in size to the Insignia (although it would be RWD).

Perhaps the most obvious route is the CTS Coupe in Opel/Vauxhall clothes?