Some bureaucrats in Mexico City tried this years ago.
An important ring road had two lanes in each direction. To increase its capacity, they didn't actually widen the road; they just repainted the lane markings to turn two lanes into three, and claimed a 50% capacity increase!
Everyone immediately screamed about being crammed together just centimetres apart, accidents increased and the city officials quickly u-turned; they repainted to have just 2 lanes in each direction again.
But they then tried to claim that as that was a 33% decrease, and that because they had earlier increased it 50%, that meant they had achieved a net 17% increase in the road's capacity!
Some links on people / groups involved:
Erica Payne
Patriotic Millionaires
Morris Pearl
There is also a Patriotic Millionaires UK