As temperatures dropped into the teens over the weekend, Dave Weaver and Thomas Ruble had no problem keeping snug by the fireplace in their East Austin, Texas, school bus.

The 1979 Bluebird International, which can rumble up to 55 mph on recycled vegetable oil, sleeps six; contains a hot-water shower, kitchen, fridge and freezer; sports floor-to-ceiling wood paneling; and features a music studio with a stand-up piano, according to the Austin American-Statesman. Click here for a link to the online video.

In the galaxy of off-the-grid living, their pad is cooler than yours.

Combining all the chi-chi style of world-class yachts — Weaver’s father was a carpenter with a Seattle-area yacht manufacturer, and the bus is outfitted with fancy scrap wood — and the environmental sensitivity you would expect of two recent college graduates from Washington state — thus the bus’s conversion to run on used vegetable oil from restaurants — the Bluebird sets a new standard in RVing.

And then there’s the penthouse, a bolted-down shell of a 1979 Volkswagen camper bus that piggybacks on top of the Bluebird. Yes, the penthouse gets great light, and opens, hatchback-like, to the bus’s picket-fenced “yard,” also known as the back half of the roof.

Looking for an adventure with an environmental bent, Weaver, 24, and Ruble, 23, friends from college, drove the bus to Austin in the late summer. At the time, they had already spent roughly $20,000 to outfit the bus, which Weaver had bought for $1,500 on Craigslist.

They picked Austin because that’s where Weaver’s brother, Ben, who had started graduate school at the University of Texas, was living.

Ben Weaver, having suffered from bus envy himself, also now lives in a veggie-oil-powered bus, adjacent to the one occupied by Dave Weaver and Ruble.

The group pays an East Austin homeowner $150 per bus per month to park, semipermanently, in the backyard. Right now both buses are plugged in, getting electricity and water from the home. They make use of beds, couches and a toilet in a next-door garage apartment, which they furnished and get to use for free for now.

When they’re on the road, “we’re like stars, especially at gas stations,” says Weaver, a tall, drawn and earnest saxophonist who records in the back of the bus.

“We have to break a picket line to get back to the front of the bus,” said Ruble, also a musician. “Everyone’s pulled out their cell phones and cameras to take pictures.”

Some of the details: The 40-foot-long, 13½-foot-tall vehicle has four 50-gallon tanks — one for conventional diesel and three for vegetable oil — and gets seven miles to the gallon. It carries a 50-gallon water tank and two 10-gallon propane tanks that power the water heater, fridge, stove and fireplace.

Besides two starting batteries on the engine of the bus, the Bluebird has solar panels and two golf-cart batteries, which power the fluorescent lights, guitar amps and computers when the bus is on the road.

For now, the pair has built a wooden fence to keep it out of public view and comply with city code. Ruble just left town with a friend on a band tour, and Weaver seems happily ensconced in his studio.

The bus serves as a test for green living, Weaver said.

“We wanted to live cheaply and lightly,” he said.