Modern gasoline compacts with small engines are very quiet at city speeds. Even on an empty street you wouldn't hear a huge difference. Tires on pavement would be an audible constant for both. On a busy street with other background noise it would be nearly impossible to distinguish the two. Certainly there's an audible difference between a hybrid and a diesel truck but you'd assume people stopped relying on audible warnings with the advent of quiet gasoline cars.
I think it's more likely that hybrids change the way some people drive. The peppy stop & go performance, combined with good braking performance, might make people more daring, more likely to accelerate quickly, more likely to rely on short stopping. This is exactly why insurance rates on sporty or high performance cars is higher than an under powered station wagon. Your choice of car changes the way you drive. If this is true it's likely that quiet gasoline compacts with good acceleration would also cause a higher number of accidents involving pedestrians.
I think it's more likely that hybrids change the way some people drive. The peppy stop & go performance, combined with good braking performance, might make people more daring, more likely to accelerate quickly, more likely to rely on short stopping. This is exactly why insurance rates on sporty or high performance cars is higher than an under powered station wagon. Your choice of car changes the way you drive. If this is true it's likely that quiet gasoline compacts with good acceleration would also cause a higher number of accidents involving pedestrians.