PALO ALTO, CA – In the 1880s, horses provided the main source of transportation, and the equivalent of today's tailpipe emissions wasn’t pretty.

Stepping outdoors in a place like New York City back then, the first thing that would hit a person was the smell from tons of horse manure on the streets. It didn’t just offend olfactory senses. It served as a breeding ground for horseflies that spread bacterial illnesses.

Describing those bygone conditions to make a point is Mercedes-Benz USA spokesman Christian Bokich. His company traces its roots to the first gasoline-powered car. Karl Benz invented it in 1885.

For Bokich, the irony is that late-19th century society hailed the advent of the internal-combustion car as both an environmental and technical breakthrough.  

“It was seen as something that was better for the environment than what it replaced,” he says of the horseless carriage.  

Today, a lot of people, including some public-policy makers and government regulators, rap internal-combustion engines for their ecological impact. Led by California, several states have enacted strict emissions controls in hopes of spurring interest in alternative fuels.

In the U.S., gasoline-powered cars still rule the road, but they’ve had some company in recent years as automakers introduce green vehicles.

The latest is the Mercedes B-Class EV. It joins seven other pure electrics on the market: the Fiat 500e, Ford Focus EV, Honda Fit EV, Nissan Leaf, Smart Fortwo ED, Tesla Model S and Toyota RAV4 EV.

The B-Class goes on sale this summer, starting in 10 “zero-emission” states, so called because of legislation aimed at reducing overall tailpipe output.

Of 15.53 million light vehicles sold last year in the U.S., 14.48 million were gasoline powered, according to WardsAuto data. EVs accounted for 49,046 units.