diff --git a/osmnx/_osm_xml.py b/osmnx/_osm_xml.py
index 26fb5bdab..89c549b77 100644
--- a/osmnx/_osm_xml.py
+++ b/osmnx/_osm_xml.py
@@ -23,6 +23,7 @@
 import networkx as nx
 import pandas as pd
 
+from . import projection
 from . import settings
 from . import utils
 from . import utils_graph
@@ -160,7 +161,7 @@ def _save_graph_xml(
     Parameters
     ----------
     G
-        Unsimplified graph to save as an OSM XML file.
+        Unsimplified, unprojected graph to save as an OSM XML file.
     filepath
         Path to the saved file including extension. If None, use default
         `settings.data_folder/graph.osm`.
@@ -211,6 +212,18 @@ def _save_graph_xml(
             else:
                 gdf[col] = gdf[col].fillna(value)
 
+    # warn user if graph is projected then remove lat/lon gdf_nodes columns if
+    # they exist, as x/y cols will be saved as lat/lon node attributes instead
+    if projection.is_projected(G.graph["crs"]):
+        msg = (
+            "Graph should be unprojected: the existing lat-lon node attributes will "
+            "be discarded and the projected x-y coordinates will be saved as lat-lon "
+            "node attributes instead. Project your graph back to lat-lon to avoid this."
+        )
+        warn(msg, category=UserWarning, stacklevel=2)
+    for col in set(gdf_nodes.columns) & {"lat", "lon"}:
+        gdf_nodes = gdf_nodes.drop(columns=[col])
+
     # transform nodes gdf to meet OSM XML spec
     # 1) reset index (osmid) then rename osmid, x, and y columns
     # 2) round lat/lon coordinates
diff --git a/osmnx/io.py b/osmnx/io.py
index 6cd000193..3817e730f 100644
--- a/osmnx/io.py
+++ b/osmnx/io.py
@@ -270,14 +270,14 @@ def save_graph_xml(
     This function merges graph edges such that each OSM way has one entry in
     the XML output, with the way's nodes topologically sorted. `G` must be
     unsimplified to save as OSM XML: otherwise, one edge could comprise
-    multiple OSM ways, making it impossible to properly group edges by way.
+    multiple OSM ways, making it impossible to group and sort edges in way.
     `G` should also have been created with `ox.settings.all_oneway=True` for
     this function to behave properly.
 
     Parameters
     ----------
     G
-        Unsimplified graph to save as an OSM XML file.
+        Unsimplified, unprojected graph to save as an OSM XML file.
     filepath
         Path to the saved file including extension. If None, use default
         `settings.data_folder/graph.osm`.
diff --git a/tests/test_osmnx.py b/tests/test_osmnx.py
index d17a83476..9c71cbd7f 100644
--- a/tests/test_osmnx.py
+++ b/tests/test_osmnx.py
@@ -164,7 +164,7 @@ def test_osm_xml() -> None:
 
     Path.unlink(Path(temp_filename))
 
-    # test .osm xml saving
+    # test OSM xml saving
     G = ox.graph_from_point(location_point, dist=500, network_type="drive", simplify=False)
     fp = Path(ox.settings.data_folder) / "graph.osm"
     ox.io.save_graph_xml(G, filepath=fp, way_tag_aggs={"lanes": "sum"})
@@ -180,14 +180,20 @@ def test_osm_xml() -> None:
     default_overpass_settings = ox.settings.overpass_settings
     ox.settings.overpass_settings += '[date:"2023-04-01T00:00:00Z"]'
     point = (39.0290346, -84.4696884)
-    G = ox.graph_from_point(point, dist=500, dist_type="bbox", network_type="drive", simplify=True)
-    with pytest.raises(ox._errors.GraphSimplificationError):
-        ox.io.save_graph_xml(G)
     G = ox.graph_from_point(point, dist=500, dist_type="bbox", network_type="drive", simplify=False)
-    nx.set_node_attributes(G, 0, name="uid")
     ox.io.save_graph_xml(G)
     _ = etree.parse(fp, parser=parser)  # noqa: S320
-    G = ox.graph_from_xml(fp)  # issues UserWarning
+
+    # raise error if trying to save a simplified graph
+    with pytest.raises(ox._errors.GraphSimplificationError):
+        ox.io.save_graph_xml(ox.simplification.simplify_graph(G))
+
+    # save a projected/consolidated graph as OSM XML
+    Gc = ox.simplification.consolidate_intersections(ox.projection.project_graph(G))
+    nx.set_node_attributes(Gc, 0, name="uid")
+    ox.io.save_graph_xml(Gc, fp)  # issues UserWarning
+    Gc = ox.graph.graph_from_xml(fp)  # issues UserWarning
+    _ = etree.parse(fp, parser=parser)  # noqa: S320
 
     # restore settings
     ox.settings.overpass_settings = default_overpass_settings