For car buyers like the Peterses – who have been vegans for more than two decades – leather-free choices are limited. The car-buying site Edmunds.com says 78 percent of 2015 model-year vehicles have standard leather seats on at least one trim level. In other words, buyers content with basic models can get cloth seats and plastic steering wheels, but as they add options like better engines, heated seats or upgraded speakers, they usually have to add leather seats.
Edmunds says 79 vehicles in the 2015 model year don't require buyers to get leather at any trim level. Those include the Toyota Prius hybrid, the BMW 3 Series and the Volkswagen Jetta. But even some models with cloth or faux-leather seats – like the plug-in hybrid Chevrolet Volt – still have leather-wrapped steering wheels.
That's not likely to change any time soon. Most customers worldwide equate leather with quality, richness and comfort, says Mel Stephens, a spokesman for automotive seat-maker Lear Corp.
"Vinyl is good, but leather is better," he said. "People like natural materials."
Luxury automakers, including Audi and Cadillac, say requests for non-leather interiors are rare. Even when they get them, high-volume automakers can't necessarily stop the assembly line and make a personalized car. Ford won't replace leather seats at the factory, for example, but says dealers can install different seats if a customer requests them.
David Peters of DLP Advisors, a leather-industry consulting firm, forecasts continued growth in automotive leather over the next decade as luxury car sales increase worldwide, particularly in China. Automakers used around 2 billion square feet of leather in 2014, or around 45 million cow hides; that was 17 percent of the global supply of hides. By 2025, that could grow to 25 percent, Peters said.
A vehicle interior usually requires two or three hides; some high-end luxury vehicles, like the Rolls Royce Phantom, use as many as nine.
Environmentalists and animal rights groups say leather tanneries pollute land and water with chemicals like chromium, which the US government classifies as a carcinogen. Raising, processing and transporting livestock also accounts for an estimated 14.5 percent of all greenhouse gas emissions, according to a 2013 report by the United Nations Food and Agriculture Organization.
Elizabeth Farrell Peters, 42, a dental hygienist and yoga instructor, became a vegetarian as a teen – and later a vegan – after growing up on a veal farm. Her husband, an airline pilot, became concerned about the inhumane treatment of animals after a visit to a slaughterhouse when he was 12. Mark Peters, 51, became a vegan in the early 1990s.
"You have to be honest about what you learn and what you know," he said. "If you put your blinders on, that makes you partially responsible."
Mark Peters was driving a BMW 3 Series with faux-leather seats when he decided to look at a Tesla Model S because he wanted an electric car. Tesla offers cloth seats on case models, but he was annoyed by the standard leather-wrapped steering wheel and the fact that he couldn't get options like heated seats without upgrading to leather. He contacted Tesla in 2012; after a little haggling, the company promised him the non-leather options he wanted at no extra cost, including a hand-built, non-leather steering wheel. He got the car in June 2013.
A year later, the couple decided to order another Tesla, but the premium package they wanted, with perks like trunk lights and a power lift gate, required them to get a leather-wrapped dashboard. This time, Tesla wouldn't budge, so they got a stripped-down, leather-free version, but weren't happy and traded it in. It wasn't until after Tesla's annual meeting in June that the company relented and let them purchase a premium, leather-free Model S.
The Peterses remain hopeful that Tesla will switch to completely leather-free interiors, a move that could have ripple effects across the industry.
"When we buy something, we vote with our dollars," Mark Peters said.
The AP contributed to this report.