Mr Allan explained that cars will generally reach classic status after about 30 years. It is at this point that they become rarer and may rise in price again.
He added: “The high-end Porsche 911s have exploded in value in recent years and people need to hold on to them.
“Also limited-run supercars (only a certain number are built to keep them exclusive) from Ferrari, McLaren, Aston Martin, Bugatti and Pagani.”
Porsche is a brand that has seen values in all models, old and new air missile for the past five years.