New General Motors Europe president Nick Reilly maintains the manufacturer's focus is firmly on brand new models rather than retro-fitting older types with modern equipment.

Speaking on the final day of this year's Challenge Bibendum sustainable mobility event at Berlin's former Tempelhof Airport, Reilly conceded upgrading existing cars with new technology was certainly possible, but was not high on GM Europe's agenda.

"To significantly change the infrastructure of an existing vehicle is quite an effort," he said. "You could retrofit stop-start [for example] but it is not cheap to do that.

"I am sure there will be certain things that come in, but from a vehicle manufacturer's point of view we are pretty focused on new cars."

And despite noting there was "a huge car park out there" that does not involve new technology, the GM Europe chief maintained he was "pretty bullish" about future development of electric vehicles for example, as well as alternative fuels.

"How many of new car sales will use new technology? - it will grow pretty rapidly," he said. They are dramatically changing the mix of car sales.

"Our challenge is to do that affordably, but that does not come for free, so not [necessarily] incentives but technology will come in faster and faster."

Reilly estimated electric vehicles could eventually take up to 20% of sales although this "could be even higher" as their current high pricing gradually fell.

"I don't think the people recognise the cost of these vehicles will come down as you get to generation two and generation three," he said.