The car, a Mercedes like the bomb discovered outside a Haymarket nightclub, was packed with a similar mix of explosives, gasoline, nails and detonators, The Times of London reported. Peter Clarke, head of Scotland Yard's counter-terrorism unit, said the two cars are clearly connected.
The second car wasn't known to contain a bomb until employees at the parking garage in Park Lane noticed a smell of gasoline.
The car bomb left outside Tiger Tiger Nightclub near Piccadilly Circus reportedly included fuel, gas cans and nails and was apparently intended to be detonated with a cell phone.
"Even at this stage it is obvious that if the device had detonated, there could have been severe injuries and loss of life," Clarke said.
An ambulance crew spotted smoke coming from the car while responding to a call at the club.
British Prime Minister Gordon Brown, who took that position Wednesday, said Britain faced "a serious and continuous threat" and the British people always "need to be alert," CNN reported.
The car bomb discovery occurred close to the second anniversary of the July 7, 2005, suicide bombings that killed 52 people and injured hundreds on London's public transportation system.