GENEVA: It starts with a loud bang. Seconds later, metre-long flames are leaping outwards from the car, sending copious amounts of thick, black soot and smoke everywhere.
To see what the impact of burning electric car batteries would be on rescue services and other nearby drivers in tunnels or car parks, the Swiss Materials Testing and Research Institute (Empa) has deliberately set a number of electric cars on fire in enclosed spaces.
The resulting video footage and findings are somewhat alarming.
"The visibility in the previously brightly lit tunnel section quickly approaches zero," the testers said, backing up their analysis with various videos of exploding electric cars.
"After a few minutes, the battery module is completely burnt out."
Their conclusion from tests: Fire departments familiar with fires in conventional cars should generally be able to deal with the fire, and the tunnel or underground car park walls and pipes should not be put at additional risk.
The problem isn't with the fire, however, rather how it's put out. The water, used in much larger quantities for electric car fires, presents a health risk.
"Under no circumstances must chemical fire-fighting water be allowed to enter the sewerage system," say the Empa experts.
Fire services say they are relieved to hear that the highly corrosive and toxic hydrofluoric acid in lithium-ion batteries used in cars did not leak in deadly levels during tests of car fires.
And yet Karl-Heinz Knorr, Vice President of the German Fire Brigade Association, admitted that battery chemicals mixing with the water used to put out the fire was indeed a problem.
Preventing this water from reaching the sewage system or ground water was easier said than done, Knorr said. In serious cases, electric car fires may force authorities to purify or cut off ground water in surrounding areas.
