Amphibian, which can reach up to 100mph on land, uses a jet to propel it through water at speeds of over 30mph.
It takes about 10 seconds for the car's wheels to retract, the power to switch and the boat to take off, says Gibbs Technologies, the company behind the car.
The accelerator can then be used as a throttle in the water.
Those who want to buy their own James Bond-style vehicle can expect to pay out about £150,000 when it goes on the market later this year.
The company chose London's Docklands, scene of a high-speed boat chase in the Bond film The World Is Not Enough, to test drive the car in public.