The government rates the Volt at 95 miles per gallon city, 93 highway, in all-electric mode.

WSJ: Is Chevy's Cruze Dulling the Spark of its Volt?

"Even though this may or may not have been spontaneous, for all we know there could be other conspirators out there, and the city should have been alerted so it could go into its defensive mode, " he said.

NPR: Police: Boston Suspects Planned To Attack New York

In this compact, canal-packed city with 400km of bike lanes and paths, the bicycle is the primary mode of transport, so visiting pedestrians need to watch out for cyclists just as much, if not more, than cars.

BBC: Living in: Amsterdam