diff --git a/include/hexagram/speedo.h b/include/hexagram/speedo.h
index a3b238d..ddedd60 100644
--- a/include/hexagram/speedo.h
+++ b/include/hexagram/speedo.h
@@ -19,7 +19,9 @@ int hexagram_speedo_init(hexagram_speedo *speedo,
                          double x,
                          double y,
                          double radius,
-                         double max_value,
-                         hexagram_speedo_units units);
+                         double max_value);
+
+void hexagram_speedo_set_units(hexagram_speedo *speedo,
+                               hexagram_speedo_units units);
 
 #endif /* _HEXAGRAM_SPEEDO_H */
diff --git a/src/cluster.c b/src/cluster.c
index d74bcf6..a26b72f 100644
--- a/src/cluster.c
+++ b/src/cluster.c
@@ -12,8 +12,7 @@
 #define SECTION_HEIGHT_TOP    64
 #define SECTION_HEIGHT_BOTTOM 52
 
-#define SPEEDO_MAX   200.0
-#define SPEEDO_UNITS HEXAGRAM_SPEEDO_MPH
+#define SPEEDO_MAX 322.0
 
 #define PATTERN_WIDTH  100
 #define PATTERN_HEIGHT  87
@@ -102,8 +101,7 @@ int hexagram_cluster_init(hexagram_cluster *cluster,
                              CLUSTER_HEIGHT / 2,
                              CLUSTER_HEIGHT / 2,
                              CLUSTER_HEIGHT / 2,
-                             SPEEDO_MAX,
-                             SPEEDO_UNITS) < 0) {
+                             SPEEDO_MAX) < 0) {
         goto error_speedo_init;
     }
 
diff --git a/src/dial.c b/src/dial.c
index 596c73b..7d91443 100644
--- a/src/dial.c
+++ b/src/dial.c
@@ -8,7 +8,7 @@
 
 #define DIAL_MAIN_BEZEL_WIDTH 16
 
-#define DIAL_RADIUS_LEGEND_MAIN   0.675
+#define DIAL_RADIUS_LEGEND_MAIN   0.69
 #define DIAL_RADIUS_LEGEND_BOTTOM 0.725
 
 #define DIAL_RADIUS_NEEDLE_MAIN_MIN 0.51
diff --git a/src/speedo.c b/src/speedo.c
index 109db21..bedf138 100644
--- a/src/speedo.c
+++ b/src/speedo.c
@@ -4,10 +4,12 @@
 #include <hexagram/gauge.h>
 #include <hexagram/speedo.h>
 
-#define SPEEDO_ANGLE_MIN 232.0 * (M_PI / 180.0)
-#define SPEEDO_ANGLE_MAX 488.0 * (M_PI / 180.0)
+#define SPEED_FACTOR_MPH 0.621371
 
-#define SPEEDO_FONT_FACE "Muli"
+#define ANGLE_MIN 232.0 * (M_PI / 180.0)
+#define ANGLE_MAX 488.0 * (M_PI / 180.0)
+
+#define FONT_FACE "Muli"
 
 static int draw_text(hexagram_speedo *speedo,
                      cairo_t *cr,
@@ -18,7 +20,7 @@ static int draw_text(hexagram_speedo *speedo,
     cairo_text_extents_t extents;
 
     cairo_select_font_face(cr,
-                           SPEEDO_FONT_FACE,
+                           FONT_FACE,
                            CAIRO_FONT_SLANT_ITALIC,
                            CAIRO_FONT_WEIGHT_BOLD);
 
@@ -39,35 +41,41 @@ static int draw_text(hexagram_speedo *speedo,
 static int draw_bg(hexagram_gauge *gauge, cairo_t *cr) {
     hexagram_speedo *speedo = (hexagram_speedo *)gauge;
 
-    int speed;
+    double factor = (speedo->units == HEXAGRAM_SPEEDO_KPH)?
+        1.0: SPEED_FACTOR_MPH;
+
+    double font_size = (speedo->units == HEXAGRAM_SPEEDO_KPH)?
+        0.085: 0.1;
+
+    int speed, max = (int)round(speedo->dial.max_value * factor);
 
     if (hexagram_dial_draw_bg(&speedo->dial, cr) < 0) {
         goto error_dial_draw_bg;
     }
 
     cairo_select_font_face(cr,
-                           SPEEDO_FONT_FACE,
+                           FONT_FACE,
                            CAIRO_FONT_SLANT_ITALIC,
                            CAIRO_FONT_WEIGHT_BOLD);
 
-    cairo_set_font_size(cr, speedo->dial.radius * 0.1);
+    cairo_set_font_size(cr, speedo->dial.radius * font_size);
     cairo_set_source_rgb(cr, 1, 1, 1);
 
-    for (speed=0; speed<=(int)speedo->dial.max_value; speed += 5) {
+    for (speed=0; speed<=max; speed += 5) {
         int large = speed % 10 == 0? 1: 0;
 
         cairo_set_line_width(cr, large? 6.0: 2.0);
-        hexagram_dial_draw_mark(&speedo->dial, cr, (double)speed, large);
+        hexagram_dial_draw_mark(&speedo->dial, cr, (double)speed / factor, large);
     }
 
-    for (speed=0; speed<=(int)speedo->dial.max_value; speed += 20) {
+    for (speed=0; speed<=max; speed += 20) {
         char buf[8];
 
         if (snprintf(buf, 8, "%d", speed) < 0) {
             goto error_snprintf;
         }
 
-        hexagram_dial_draw_legend(&speedo->dial, cr, speed, buf);
+        hexagram_dial_draw_legend(&speedo->dial, cr, (double)speed / factor, buf);
     }
 
     return 0;
@@ -80,18 +88,25 @@ error_dial_draw_bg:
 static int draw_fg(hexagram_gauge *gauge, cairo_t *cr) {
     hexagram_speedo *speedo = (hexagram_speedo *)gauge;
     char buf[8];
+    double factor = (speedo->units == HEXAGRAM_SPEEDO_KPH)?
+        1.0: SPEED_FACTOR_MPH;
 
     if (hexagram_dial_draw_fg(&speedo->dial, cr) < 0) {
         goto error_dial_draw_fg;
     }
 
-    if (snprintf(buf, sizeof(buf), "%d", (int)speedo->dial.value) < 0) {
+    if (snprintf(buf, sizeof(buf), "%d", (int)(speedo->dial.value * factor)) < 0) {
         goto error_snprintf;
     }
 
     draw_text(speedo, cr, gauge->x, gauge->y - speedo->dial.radius * 0.01, buf, 0.32);
 
-    draw_text(speedo, cr, gauge->x, gauge->y + speedo->dial.radius * 0.2, "mph", 0.1);
+    draw_text(speedo,
+              cr,
+              gauge->x,
+              gauge->y + speedo->dial.radius * 0.2,
+              speedo->units == HEXAGRAM_SPEEDO_KPH? "kph": "mph",
+              0.1);
 
     return 0;
 
@@ -104,15 +119,14 @@ int hexagram_speedo_init(hexagram_speedo *speedo,
                          double x,
                          double y,
                          double radius,
-                         double max_value,
-                         hexagram_speedo_units units) {
+                         double max_value) {
     if (hexagram_dial_init(&speedo->dial,
                            HEXAGRAM_DIAL_MAIN,
                            x,
                            y,
                            radius,
-                           SPEEDO_ANGLE_MIN,
-                           SPEEDO_ANGLE_MAX,
+                           ANGLE_MIN,
+                           ANGLE_MAX,
                            0,
                            max_value) < 0) {
         goto error_dial_init;
@@ -120,10 +134,20 @@ int hexagram_speedo_init(hexagram_speedo *speedo,
 
     speedo->dial.gauge.draw_bg = draw_bg;
     speedo->dial.gauge.draw_fg = draw_fg;
-    speedo->units = units;
+    speedo->units              = HEXAGRAM_SPEEDO_KPH;
 
     return 0;
 
 error_dial_init:
     return -1;
 }
+
+void hexagram_speedo_set_units(hexagram_speedo *speedo,
+                               hexagram_speedo_units units) {
+    switch (units) {
+        case HEXAGRAM_SPEEDO_KPH:
+        case HEXAGRAM_SPEEDO_MPH:
+            speedo->units = units;
+            break;
+    }
+}