The average USA pedestrian fatality rate from 1994-1999 was 5,335/year. Hybrid electric vehicles first showed up in 2000 and looking at
2001-2006, the average rate has been 4,813/year. Nationwide there has been a significant increase in hybrid electric vehicles but the pedestrian fatality averages are lower. In 2006 there were 4,784 pedestrian fatalities. Anyone looking at cause and effect would wonder why hybrids have not caused more pedestrian fatalities.In California, a state with a large percentage of hybrids, the numbers have been and remain modest for 2002-2006. Only California bicyclists have suffered a significant increase in 2006 but that could be simply people trying to save gas forgetting that on a bicycle they are invisible to traffic.
Hybrid owners tend to be more interested in saving fuel and often drive at slower speeds. If you check various car forums, you can easily find gas-only drivers complaining about "slow Prius" or other hybrid drivers. Speed kills and especially around pedestrians.
Hybrid drivers noticed early on that their cars are often not heard and take extra care in parking lots and places with pedestrians. Putting a noise maker on hybrids encourages the same complacency of today's noisy car drivers who drive as if their engine noise means they have the right-of-way and pedestrians should get out of the way. This simply returns us to the 5,300 pedestrian fatalities per year of the 1990s or today's louder car drivers who assume they will be heard and pedestrians should get out of the way.
There is a serious problem of too many pedestrian and bicyclist accidents per year. But to think 'sound alone' will solve the problem aborts a serious analysis and effective solutions. The last sound you may hear is the faux engine noise of a hybrid driver who believes you will get out of their way . . . like the noisy car drivers of today.
Bob Wilson