He points out that sedans are aerodynamically more efficient than SUVs, something that will help in the quest to reduce emissions and consumption.
Electrification is also a key area. "I think we should electrify everything," says Callum.
That is already on the cards, with Jaguar Land Rover CEO Ralf Speth confirming to us last month that the company will embark on an electrification strategy from 2020.
Like Speth and other industry leaders, Callum is unhappy with some of the political decisions taking place. He says politicians need to think their policies through properly, revealing that many changes taking place in the industry have "been forced upon us".
Whatever the rationale behind the political decisions, there are significant changes taking place and Callum says that the engineering division is keen to match design when it comes to future models, but says "physics will only go so far, and chemistry".
An example is including the batteries in any design. How batteries in the floor evolve is quite challenging, but he and his team is trying to influence the outcome, he says.
There is an incredible opportunity with battery technology but cars are going to have to get taller in order to accommodate it, Callum says.
And what about electrification of older models? Jaguar recently unveiled a battery-electric version of the iconic E-Type. Callum is not convinced but he has driven it and says he was "impressed by how much like an E-Type it felt".