diff --git a/compareUpscaling.cmake b/compareUpscaling.cmake
index ecf01e5..a467e42 100644
--- a/compareUpscaling.cmake
+++ b/compareUpscaling.cmake
@@ -109,6 +109,7 @@ macro (add_test_upscale_elasticity gridname method)
                            ${abstol} ${reltol} 
                TEST_ARGS output=${RESULT_PATH}/upscale_elasticity_${method}_${gridname}.txt
                          gridfilename=${INPUT_DATA_PATH}/grids/${gridname}.grdecl
+                         output_wave_speeds=true
                          method=${method})
 endmacro (add_test_upscale_elasticity gridname method rows)
 
diff --git a/examples/upscale_elasticity.cpp b/examples/upscale_elasticity.cpp
index ef64682..0f37da5 100644
--- a/examples/upscale_elasticity.cpp
+++ b/examples/upscale_elasticity.cpp
@@ -141,6 +141,8 @@ struct Params {
   int cellsz;
   //! \brief verbose output
   bool verbose;
+  //! \brief Output wave speeds as data. For reg-test comparison purposes.
+  bool outputSpeeds;
   //! \brief Run a inspection only, currently 'mesh, results, load'
   std::string inspect;
   //! \brief Result template filename (input/output)
@@ -180,6 +182,7 @@ void parseCommandLine(int argc, char** argv, Params& p)
   p.resultfilename  = param.getDefault<std::string>("resultfilename","");
   p.output   = param.getDefault<std::string>("output","");
   p.verbose  = param.getDefault<bool>("verbose",false);
+  p.outputSpeeds = param.getDefault<bool>("output_wave_speeds",false);
   p.inspect  = param.getDefault<std::string>("inspect","");
   size_t i;
   if ((i=p.vtufile.find(".vtu")) != std::string::npos)
@@ -269,7 +272,9 @@ void writeOutput(const Params& p, Opm::time::StopWatch& watch, int cells,
 
   f << "#" << std::endl
     << "######################################################################" << std::endl
-    << C << std::endl;
+    << C;
+  if (p.outputSpeeds && upscaledRho > 0)
+    f << upscaledRho << " " << speeds << std::endl;
 }
 
 //! \brief Main solution loop. Allows templating over the AMG type
diff --git a/tests/input_data/grids/EightCells.grdecl b/tests/input_data/grids/EightCells.grdecl
index 1f322ae..3fce8b3 100644
--- a/tests/input_data/grids/EightCells.grdecl
+++ b/tests/input_data/grids/EightCells.grdecl
@@ -50,3 +50,7 @@ PORO
 SATNUM
   1  2  1  1  2  2  2  2
 /
+
+RHO
+  1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0
+/
diff --git a/tests/input_data/reference_solutions/upscale_elasticity_mortar_EightCells.txt b/tests/input_data/reference_solutions/upscale_elasticity_mortar_EightCells.txt
index 0982d5c..75ab993 100644
--- a/tests/input_data/reference_solutions/upscale_elasticity_mortar_EightCells.txt
+++ b/tests/input_data/reference_solutions/upscale_elasticity_mortar_EightCells.txt
@@ -31,4 +31,4 @@
 0.00886555 0.00488502 -0.00387763 3.01119 0.00586288 0
 0.00916403 -0.0144548 0.00900469 0.00586288 3.07441 0
 0 0 0 0 0 3.69018
-
+3.5 2.73658 1.92098 1.75339
diff --git a/tests/input_data/reference_solutions/upscale_elasticity_mpc_EightCells.txt b/tests/input_data/reference_solutions/upscale_elasticity_mpc_EightCells.txt
index 34f7606..b65e41a 100644
--- a/tests/input_data/reference_solutions/upscale_elasticity_mpc_EightCells.txt
+++ b/tests/input_data/reference_solutions/upscale_elasticity_mpc_EightCells.txt
@@ -31,4 +31,4 @@
 0 0 0 3.01461 0 0
 0 0 0 0 3.08606 0
 0 0 0 0 0 3.69018
-
+3.5 2.73973 1.92098 1.75672