Bentley's chief of sales and marketing, Kevin Rose, says that around the world every year 40,000 cars are sold at a price higher than S$250,000.

He says that number is growing solidly, though he won't predict the actual rate because some very important billionaire-producing nations, such as China and Russia, are politically and economically uncertain. But he notes that Bentley has a 40 per cent share of that 40,000-car market.

The other crucial trend in posh cars, indeed in all cars, is the shift to crossovers and SUVs. Obviously Bentley has reacted to that, because it's announced its own SUV. It's due on sale in 2016.

What about Rolls-Royce? Peter Schwarzenbauer, the BMW board member in charge of Rolls-Royce (as well as Mini and motorbikes) told Top Gear: "There are long-term independent studies that say half the world car market – 50 per cent of everything – will be crossovers and SUVs. So it's our responsibility to look into it. We are seriously analysing a Rolls-Royce in the SUV area."

But Schwarzenbauer won't say it's decided. "We have to know it would still be a true Rolls-Royce. If we're not convinced it is, then I will not ask the board for permission to go forward with it. So the question is, does it fit to the Rolls-Royce brand? They had the same discussions at BMW before they made the first X5. No doubt at Porsche before the Cayenne too."

Which is a pretty heavy hint. Schwarzenbauer once ran Porsche's North American arm, where the Cayenne was a huge hit. He also points out that 40 percent of BMW's sales are now the X-models.

Yup, no posh-car company ever burnt its fingers building an SUV, so you've got to assume the question is not 'if' but 'when' and 'how' they do the R-R SUV.

Back to Bentley. Kevin Rose explains why Bentley (and indeed Rolls-Royce or Ferrari or Aston and the rest) can't just rely on a small number of models. The rich want a car their equally rich friends don't have. "Exclusivity means we mustn't have too many of one model in one place. So we need to be more global, and to have more models."

So he talks about the possibility of another Bentley model line beyond the SUV. "We'll get the SUV and then we'll have to replace the Continental GT and Flying Spur. After that we're not short of ideas, and a smaller car could be attractive. But smaller doesn't necessarily mean much cheaper. I can't see us going below £100,000. We'll have to look at what customers need. We can't bring it to market until after 2019."

We already know that the Bentley designers have worked up ideas for a sports car. But Rose clarifies a bit about what a Bentley sports car would be. "The Bentley brand is, and has been for some while, luxury and performance blended better than anyone else. We'd never try to make a Ferrari. But we could go against Maserati and Aston Martin."

What about extra body styles for the Mulsanne? After all, Rolls-Royce builds convertible and coupe versions of the Phantom. Bentley itself once built the Azure soft-top and and Brooklands two-door off the old Arnage saloon.

Rose implies new Mulsanne relatives are likely. "Yes the Mulsanne is important for the brand and good business at 1000 cars a year. I have ideas to expand it. And we have put a new team behind Mulliner [the coachbuilding arm]."

What about different powertrains? Rolls-Royce won't remain a V12-only company. There was an electric Phantom research car, but that came to nothing because its range wasn't enough.

Schwarzenbauer says: "Fully electric is not viable for a Rolls-Royce now." Only an unexpected new battery technology would be make it feasible. "But plug-in hybrid is a technology we have to look at. In future more and more cities will have zero-emission zones, so a Rolls-Royce will need 20-30 miles of electric range."

Over at Bentley several executives have said the same thing about plug-in tech, especially in context of the SUV. Bentley did well by adding the V8 to its Continental and Spur ranges: Bentley drivers wouldn't admit they fret about fuel cost, but the extra tank range for the V8 is handy.

And VW Group boss Martin Winterkorn has said a diesel is also very likely for Bentley. Rose won't elaborate exactly what engine or when. "It's not yet exactly decided. But if we do it, it has to be better than the rest."