Aston Martin unveils $4 million concept submarine 
British automaker Aston Martin in collaboration with the US-based Triton Submarines on Thursday unveiled a concept submarine. Called the 'Project Neptune', it is based on Triton's three-person submarine platform and will cost around $4 million. The "strictly-limited edition" vehicle will reportedly be 5.9 feet tall and will travel at the speed of 5.6 kilometre per hour.