diff --git a/Tools/autotest/apmrover2.py b/Tools/autotest/apmrover2.py
index d84e5a328d..b094685090 100644
--- a/Tools/autotest/apmrover2.py
+++ b/Tools/autotest/apmrover2.py
@@ -83,16 +83,10 @@ def drive_APMrover2(viewerip=None, map=False):
     if map:
         options += ' --map'
 
-    sim_cmd = util.reltopdir('Tools/autotest/pysim/sim_wrapper.py') + ' --frame=rover --rate=200 --speedup=100 --home=%f,%f,%u,%u' % (
-        HOME.lat, HOME.lng, HOME.alt, HOME.heading)
-
-    sil = util.start_SIL('APMrover2', wipe=True)
+    home = "%f,%f,%u,%u" % (HOME.lat, HOME.lng, HOME.alt, HOME.heading)
+    sil = util.start_SIL('APMrover2', wipe=True, model='rover', home=home, speedup=10)
     mavproxy = util.start_MAVProxy_SIL('APMrover2', options=options)
 
-    runsim = pexpect.spawn(sim_cmd, logfile=sys.stdout, timeout=10)
-    runsim.delaybeforesend = 0
-    runsim.expect('Starting at lat')
-
     print("WAITING FOR PARAMETERS")
     mavproxy.expect('Received [0-9]+ parameters')
 
@@ -103,9 +97,8 @@ def drive_APMrover2(viewerip=None, map=False):
     # restart with new parms
     util.pexpect_close(mavproxy)
     util.pexpect_close(sil)
-    util.pexpect_close(runsim)
 
-    sil = util.start_SIL('APMrover2')
+    sil = util.start_SIL('APMrover2', model='rover', home=home, speedup=10)
     mavproxy = util.start_MAVProxy_SIL('APMrover2', options=options)
     mavproxy.expect('Logging to (\S+)')
     logfile = mavproxy.match.group(1)
@@ -114,11 +107,6 @@ def drive_APMrover2(viewerip=None, map=False):
     sim_cmd = util.reltopdir('Tools/autotest/pysim/sim_wrapper.py') + ' --frame=rover --rate=200 --speedup=100 --home=%f,%f,%u,%u' % (
         HOME.lat, HOME.lng, HOME.alt, HOME.heading)
 
-    runsim = pexpect.spawn(sim_cmd, logfile=sys.stdout, timeout=10)
-    runsim.delaybeforesend = 0
-    util.pexpect_autoclose(runsim)
-    runsim.expect('Starting at lat')
-
     buildlog = util.reltopdir("../buildlogs/APMrover2-test.tlog")
     print("buildlog=%s" % buildlog)
     if os.path.exists(buildlog):
@@ -133,7 +121,7 @@ def drive_APMrover2(viewerip=None, map=False):
     util.expect_setup_callback(mavproxy, expect_callback)
 
     expect_list_clear()
-    expect_list_extend([runsim, sil, mavproxy])
+    expect_list_extend([sil, mavproxy])
 
     print("Started simulator")
 
@@ -176,7 +164,6 @@ def drive_APMrover2(viewerip=None, map=False):
     mav.close()
     util.pexpect_close(mavproxy)
     util.pexpect_close(sil)
-    util.pexpect_close(runsim)
 
     if os.path.exists('APMrover2-valgrind.log'):
         os.chmod('APMrover2-valgrind.log', 0644)
diff --git a/Tools/autotest/autotest.py b/Tools/autotest/autotest.py
index 1bd3c84338..32201ff020 100755
--- a/Tools/autotest/autotest.py
+++ b/Tools/autotest/autotest.py
@@ -144,6 +144,7 @@ parser.add_option("--viewerip", default=None, help='IP address to send MAVLink a
 parser.add_option("--map", action='store_true', default=False, help='show map')
 parser.add_option("--experimental", default=False, action='store_true', help='enable experimental tests')
 parser.add_option("--timeout", default=3000, type='int', help='maximum runtime in seconds')
+parser.add_option("-j", default=1, type='int', help='build CPUs')
 
 opts, args = parser.parse_args()
 
@@ -201,13 +202,13 @@ def run_step(step):
         return test_prerequisites()
 
     if step == 'build.ArduPlane':
-        return util.build_SIL('ArduPlane')
+        return util.build_SIL('ArduPlane', j=opts.j)
 
     if step == 'build.APMrover2':
-        return util.build_SIL('APMrover2')
+        return util.build_SIL('APMrover2', j=opts.j)
 
     if step == 'build.ArduCopter':
-        return util.build_SIL('ArduCopter')
+        return util.build_SIL('ArduCopter', j=opts.j)
 
     if step == 'defaults.ArduPlane':
         return get_default_params('ArduPlane')
diff --git a/Tools/autotest/pysim/util.py b/Tools/autotest/pysim/util.py
index 8ba3bfdf68..86ea89654a 100644
--- a/Tools/autotest/pysim/util.py
+++ b/Tools/autotest/pysim/util.py
@@ -58,12 +58,12 @@ def deltree(path):
 
 
 
-def build_SIL(atype, target='sitl'):
+def build_SIL(atype, target='sitl', j=1):
     '''build desktop SIL'''
     run_cmd("make clean",
             dir=reltopdir(atype),
             checkfail=True)
-    run_cmd("make %s" % target,
+    run_cmd("make -j%u %s" % (j, target),
             dir=reltopdir(atype),
             checkfail=True)
     return True
@@ -105,7 +105,7 @@ def pexpect_drain(p):
     except pexpect.TIMEOUT:
         pass
 
-def start_SIL(atype, valgrind=False, wipe=False, height=None, synthetic_clock=True):
+def start_SIL(atype, valgrind=False, wipe=False, height=None, synthetic_clock=True, home=None, model=None, speedup=1):
     '''launch a SIL instance'''
     import pexpect
     cmd=""
@@ -121,6 +121,12 @@ def start_SIL(atype, valgrind=False, wipe=False, height=None, synthetic_clock=Tr
         cmd += ' -H %u' % height
     if synthetic_clock:
         cmd += ' -S'
+    if home is not None:
+        cmd += ' --home=%s' % home
+    if model is not None:
+        cmd += ' --model=%s' % model
+    if speedup != 1:
+        cmd += ' --speedup=%f' % speedup
     ret = pexpect.spawn(cmd, logfile=sys.stdout, timeout=5)
     ret.delaybeforesend = 0
     pexpect_autoclose(ret)