The Green New Deal is long on vision but skimpy on details. It calls for a sweeping overhaul of America’s transportation system and the replacement of fossil fuels with zero-emission energy, but doesn’t say much about what such a system would look like. Or how we could pay for it.

But maybe the vagueness is by design. It’s simply a target we’re going to have to reach, advocates say, given climate change imperatives. The key transportation winners in the legislation, as introduced by Rep. Alexandria Ocasio-Cortez, D-N.Y., and Sen. Edward Markey, D-Mass., are “zero-emission vehicle infrastructure and manufacturing,” “clean, affordable and accessible public transit” and “high-speed rail.” Not much is said about supporting ridesharing, bike lanes, carpooling or telecommuting, all seen as ways to take cars off the road. (In reality, ridesharing may be doing the opposite.)

The bill calls for “overhauling transportation systems in the U.S. to remove pollution and greenhouse gas emissions from the transportation sector as much as technologically feasible.” That last provision is, obviously, subject to debate. What’s feasible isn’t always affordable, or politically viable.

Almost none of this New Deal’s proposals could pass in the current Congress, even in watered-down form, but 2020 could change the political balance. So what would the Green New Deal mean for transportation?

A lengthy summary of the bill posted by supporters (in this case, specifically the Green Party) calls for a “complete phase-out of fossil fuels, fracked [natural] gas and nuclear power,” with a transition to “100 percent clean energy” (presumably a mix of solar and wind) by 2030. It calls for replacing “non-essential individual means of transport with high-quality and modern mass transit.” And it adds that “it will be necessary to electrify everything else, including transport, heating, etc.”

Remarkably, there are very few credible studies that look at how the planet could actually get to a zero-emission energy economy — especially without natural gas or nuclear power. The latter two sources provide baseline energy, meaning they’re always “on.” Wind and solar are both intermittent, which means to keep the lights on we’d need a national grid that can move electricity quickly around the country. And, of course, that doesn’t exist.

One of the few existing plans, cited in the Green New Deal, is from Mark Jacobson, a professor at Stanford, and Mark Delucchi, a research scientist at the University of California, Davis. “Our plan calls for millions of wind turbines, water machines and solar installations,” they said in Scientific American. “The numbers are large, but the scale is not an insurmountable hurdle; society has achieved massive transformations before.”

They’re not kidding about large numbers — their plan imagines 3.8 million large wind turbines, 90,000 utility-scale solar plants, 490,000 tidal turbines, 5,350 geothermal installations and 900 hydroelectric plants. Getting there by 2050, as the plan imagines, would require a united planet with a common goal, and zero NIMBY opposition (such as derailed the Cape Wind Project in Massachusetts).

The World Wildlife Federation agrees that a renewable energy economy is an achievable goal, but over “the next four decades.”

But even these ambitious plans fall afoul of the relentless imperatives of a warming world. The Intergovernmental Panel on Climate Change (IPCC) said last year we have about a dozen years to reduce greenhouse emissions and avoid the most catastrophic consequences of climate change. Transportation (accounting for a third of those emissions in the U.S., less globally) is making progress, but nowhere near what the Green New Deal envisions. The 361,307 battery electric and plug-in hybrid vehicles sold in the U.S. last year were less than 2 percent of the 17.27 million cars and trucks sold. With more EV models on offer and increased range, global consultancy McKinsey and Co. thinks EVs’ percentage of the total vehicle market could grow to a whopping 14 percent by 2030.

So the Green New Deal imagines a great leap forward, from a slow, voluntary shift to electrified transportation to a swift, mandated one. “We need to act fast and mobilize, and we have no other option but to set these targets if we’re going to avoid climate chaos,” Hana Creger, environmental equity program manager for the Greenlining Institute, told Autoblog. “We know it’s ambitious, but the level of ambition of the Green New Deal for transportation is absolutely on point, given the scale of the problem.”

Creger thinks we can learn from California, which makes up half of U.S. EV adoption and 32 percent of its renewable energy. She adds that the state’s EV subsidies are equitable (a big part of the Green New Deal), providing rebates targeted at low-income earners.

The conservative Heritage Foundation is, not surprisingly, skeptical. “Do you want the federal government to control what kind of car you drive and what kind of energy you buy?” it asks. “Because the end goal of the Green New Deal is to eliminate the use of coal, oil, natural gas, nuclear and the internal-combustion engine.”

Heritage writes that these sources currently “provide 83 percent of America’s electricity and 92 percent of the transportation fuel market. So the costs of a green transformation would be astronomical.”

They would indeed, but left unsaid is that the costs — economic and otherwise — of catastrophic climate change would be far greater.

One of the key issues here is choice. Americans have it, and so far they’re choosing SUVs over EVs. And while the nation’s public transit system is expanding rapidly, it’s still a big challenge in a country that’s as spread out as the U.S. (especially when compared to Europe). Creger acknowledges this. “Perhaps in cities we’ll see enhanced public transit, walking and biking, and in rural and suburban areas more of an emphasis on electric vehicles,” she said. So far, though, EVs have been challenged in rural areas because of range issues.

Public transit never pays for itself out of the fare box, and in some places that basic fact has been used to stop projects in their tracks — and is a constant threat to the national rail network, Amtrak. High-speed rail has also been hurt by cost overrun projections and shut down, even in California under the ultra-liberal new governor, Gavin Newsom.

At last count the Green New Deal had 90 co-sponsors in the House, all of them Democrats. As legislation, it doesn’t have much chance of becoming law. As constituted, the bill is a progressive wish list, with provisions on everything from supporting family farming to “repairing historic oppression of indigenous peoples” and cleaning up hazardous waste sites.

Ocasio-Cortez and Markey want Americans to dream bigger dreams, to raise their expectations. Most of the auto industry actually is planning for a switch to electric vehicles, though few would think that transition will be completed as early as 2030. Some analysts worry that if the U.S. lags on EV leadership, the automotive center of gravity will shift to other countries.

In reality, what is likely to happen is that electrification will accompany a market-driven shift to ACES — cars and trucks that are autonomous, connected, electric and, of course, shared. In that scenario, Americans won’t actually own cars, and vehicle choice will shift to fleet buyers. If that scenario unfolds, and many believe it will, tailpipes will disappear without a mandate, and consumers will be thrilled with their new mobility.

Affordable public transit for all and a national network of high-speed rail? That might have to wait for a while.