Carbon monoxide has occasionally been described as a silent killer, and the recent deaths of a New York man and a woman in Florida prove the phrase still runs true in modern cars.

Chasity Glisson, 29 from Fort Lauderdale, Florida and Ernest Codelia, 79 from Queens, New York are two victims of the silence of a modern engine.

Miss Glisson died after leaving her Toyota running in the garage of her town house. The near silence of a modern combustion engine was partly to blame, as was the ease of which the car could be started - via a high-tech key. The victim's mother, Kimberlin Nickles, says the new key no longer requires drivers to turn it to turn off the engine and motorists used to the old process may forget in newer vehicles.

"[The system] requires a change to basic and deep-rooted consumer behavior... [this] may lead to foreseeable errors, such as mistakenly leaving the vehicle running after exiting". Nickles is seeking compensation of more than $15,000 from Toyota.

Mr Codelia also died after his partner, Mary Rivera, left her Toyota running in her garage. Miss Rivera is also suing Toyota.

Toyota has responded to the cases by saying that their electronic key system complies with all federal standards and does offer both visual and auditory warnings. The company adds: "Toyota sympathizes with the families of anyone injured as a result of exposure to carbon monoxide".

However clean engines become these days, they do still emit dangerous gases and we do emphasize the risk of leaving them running in a confined space. If you have a particularly quiet car, we suggest getting into a particular routine before you exit the car to prevent tragedies like those above.

[The Telegraph]