Green Mountain National Forest: https://www.fs.usda.gov/Internet/FSE_MEDIA/stelprdb5318739.pdf
Unexpected...New York is far more generous with dispersed car camping, as long as you use designated sites:
From this excellent Reddit reply:
Yes, it is possible. There's plenty of free, first-come, first-serve roadside campsites across the Adirondack Park. The best place to do this, as recommended by /u/Drizzle11M, is the Moose River Plains complex- there's 100+ free designated roadside campsites spread throughout miles and miles of old logging roads through a remote area.Haven't found a good list like that, but did find that the Catskills follow the same "Yellow Disk" designated camping site system :)
Some other options include the following. This is a lengthy list but it is far from complete:
Jones Pond, in the northern ADKs, has about a half dozen or so designated tent sites that are either car accessible or a short walk from the road.
Mountain Pond, in the northern ADKs, has a few designated tent sites just off the road.
Slush Pond Road, in the northern ADKs has a number of car accessible designated sites.
The Lake Kushaqua area in the northern ADKs has a couple of roadside/close to roadside designated sites.
Floodwood Road, in the Saranac Lake area, has a number of designated roadside tent sites.
South Meadows Road, just off the road to the Adirondak Loj, has about a dozen or so designated roadside sites (plus a few more than are a short walk off the road). However, fires are prohibited here and bear canisters are required (see more on this below). There's a small number of roadside/close to roadside sites near the junction of Routes 9 and 73 in St. Huberts. Nearby, Chapel Pond also has a couple of roadside/close to roadside sites. (Note that bear canisters will be required at some of these sites in the near future- see more on this below.)
In the Western High Peaks, Coreys Road has a bunch of designated roadside sites.
Dacy Clearing Road, near Lake George, has a number of roadside designated sites.
The Hudson River Recreation Area, near Warrensburg, has a number of roadside designated sites.
There's a bunch of roadside/close to roadside designated sites along Route 8, adjacent to the East Branch Sacandaga River and along the southern boundary of the Siamese Ponds Wilderness.
There are plans to add about 10 or so roadside/close to roadside sites on the road into Boreas Ponds, on the south side of the High Peaks Wilderness.
The road to the Deer Pond access for the Essex Chain from Newcomb has 6 roadside/close to roadside designated sites.
Both Moose Pond Way and Northwoods Club Road in the central ADKs have a number of roadside designated tent sites.
Mason Lake, just south of Lewey Lake in the central ADKs has about a half dozen or so roadside designated sites.
There's a number of roadside designated sites along West River Road in Wells, in the southern ADKs.
Powley-Piseco Road in the southern ADKs also has a bunch of roadside designated sites.
I believe there's a few roadside designate sites at North Lake, on the North Lake Tract Easement in the southwestern ADKs. Moss Lake, near Old Forge, has a bunch of designated tent sites- some are quite close to the parking lot at the trailhead. Horseshoe Lake, near Tupper Lake in the northwest ADKs has a bunch of designated roadside tent sites.
There's a number of roadside designated tent sites along Bear Pond Road and Number 1 Road in the Watson's East Triangle Wild Forest, in the northwest ADKs.
However, a few things to be aware of:
Make sure you know and understand the so called "150 foot rule." In the ADKs, camping is restricted within 150 feet of any roads, trails, or water bodies- within these buffers, you can only camp at officially designated sites. This means that you can't just pull over the side of the road at any and every spot you think looks nice and set up a car camp- it has to be a designated site. Officially designated sites are marked with a yellow plastic disc that says "Camp Here." Adhering to this regulation is super important as it helps to minimize adverse impacts on backcountry resources.
When dispersed camping in the ADKs, you are limited to a maximum group size of 9 people (8 people in some areas). You're also limited to a maximum length of stay at any campsite of 3 consecutive nights. For some areas, you can get a permit from the DEC for a larger group and/or a longer lengthy of stay (you'd want to contact the DEC several weeks in advance of your trip to ask about getting a permit). Some areas of the ADKs- including areas with roadside campsites- don't allow fires, and/or require the use of bear canisters for overnight food storage. Realistically, no ranger is going to hassle you for not having a bear canister provided that your food is stored out of sight in your vehicle, but you do need to be extra careful with food in these areas nonetheless. And the fire bans were implemented due to years of illegal tree cutting by campers and it's really important to abide by the ban- these areas get so much use that there literally is not enough dead and downed wood to sustain campfires by all users. (The Moose River Plains does not have either of these regulations.)
Many of the options for dispersed car camping in the ADKs are on seasonal dirt roads. In a normal season, most of these roads are open by late May- but after a particularly long winter, some may not open until sometime in June. So if you're planning on an early season trip, you'll need to do some careful research on road closures. (Also, be aware that the Moose River Plains has a regulation requiring either 4WD or tire chains for any vehicle entering the area after Columbus Day.) Opportunities for free roadside camping in the ADKs tend to be popular- and many of these areas do fill up every Thursday/Friday during the warmer months as weekend users make their way into the ADKs. It's worth trying to get a jump on the weekend if you want a solid chance at securing a nice site for yourself. Even the Moose River Plains, with it's 100+ sites, filled to capacity a few times last summer. And even with an early arrival, definitely have some backup plans in mind for if/when every site in a specific area is already occupied.