diff --git a/fastsim-core/src/drive_cycle.rs b/fastsim-core/src/drive_cycle.rs
index a82161b4..f0182c1d 100644
--- a/fastsim-core/src/drive_cycle.rs
+++ b/fastsim-core/src/drive_cycle.rs
@@ -51,6 +51,7 @@ pub struct Cycle {
     /// ambient air temperature w.r.t. to time (rather than spatial position)
     #[serde(default, skip_serializing_if = "Vec::is_empty")]
     pub temp_amb_air: Vec<si::Temperature>,
+    // TODO: add provision for optional time-varying aux load
 }
 
 lazy_static! {
diff --git a/fastsim-core/src/vehicle/hev.rs b/fastsim-core/src/vehicle/hev.rs
index 9f31305e..6391f00d 100644
--- a/fastsim-core/src/vehicle/hev.rs
+++ b/fastsim-core/src/vehicle/hev.rs
@@ -595,6 +595,12 @@ impl HEVPowertrainControls {
             fc_state.pwr_prop_max.get::<si::kilowatt>()
         );
 
+        // # Brain dump for thermal stuff
+        // TODO: engine on/off w.r.t. thermal stuff should not come into play
+        // if there is no component (e.g. cabin) demanding heat from the engine.  My 2019
+        // Hyundai Ioniq will turn the engine off if there is no heat demand regardless of
+        // the coolant temperature
+        // TODO: make sure idle fuel gets converted to heat correctly
         let (fc_pwr, em_pwr) = match self {
             Self::RGWDB(ref mut rgwdb) => {
                 handle_fc_on_causes_for_temp(fc, rgwdb, hev_state)?;