SafeDriver Review part 2
Using the system and trying to cheat its
is quite literally a 'black box' that simply plugs into your
vehicle's OBD-II port and then transmits data to the
Part 2 of a two part review
of the Lemur SafeDriver system. Please see part 1 for
an explanation of what the
SafeDriver is, what it does and how and why.
The Lemur SafeDriver system
elegantly combines simplicity with affordability. It does
not pretend to be a fully featured monitoring system and it does
not give you a vast array of data about the monitored vehicle
and driver's performance, but it gives you enough for a vague
approximate understanding of what is going on, and - perhaps
most valuably - introduces an element of accountability into
your teen's driving behavior.
It has a recommended retail
price of $69.95 and is available from
for $56.13. There are no ongoing monthly costs.
A great little gadget,
yourself, or for anyone with teenage drivers.
Using the SafeDriver
(Please see the
first part of this review for
introductory comments, description, etc, of the unit.)
Using the SafeDriver is very
simple. Once installed, the sensor/transmitter is always
either in a standby mode or an 'on/transmitting' mode.
There is nothing to switch on/off, and nothing else you need to
do or activate or remember.
Because of the sensor
expecting to be always connected, if the unit
is ever disconnected, its state changes from on or standby to
off/disconnected, and so when it is reconnected again, it sends
an 'I was unplugged' warning to the fob/receiver. Of
course, most of the time, such a message indicates that someone
was trying to cheat the system.
The only possible valid
indicator would be if the vehicle's battery was removed so that
the sensor loses all standby power - it would not be able to
distinguish between this and a disconnect. But of course,
it is unlikely that there's be a bona fide battery removal
during the course of an ordinary day's driving by someone you
are wishing to monitor.
If the fob is in the car
while it is being driven, it gets updates every 30 seconds to
update its data. You can also force an update simply by
pressing its reset button if you can't wait 30 seconds - this
was helpful for me when testing the unit, but it is probably not
something you'd need to do much in ordinary use.
A good added feature is that
it is possible to operate the car without the fob/receiver being
present. When the fob is then reunited with the car
subsequently, the transmitter will update the fob with all the
data it had missed.
The sensor/transmitter is
storing the information that it downloads to the receiver/fob
when the two are able to communicate each other, and the sensor
unit has enough storage capacity to save trip information up to
9999 miles and up to 99 braking events (plus of course whatever
the maximum speed is since it was last reset). So you
could lend your car to someone for weeks at a time and still get
a full update of driving data when you (and the receiver/fob)
are reunited with the vehicle subsequently.
Car Battery Drain
The sensor/transmitter is
always on, and so is always taking a small amount of power from
the vehicle's battery.
The amount of power being
taken depends on the vehicle and its particular type of OBD-II
implementation, but most more modern vehicles (using the CAN
type of OBD-II data, in case you wondered) will experience a 9.5
mA power drain.
What does this mean?
It means that the SafeDriver is drawing just under a quarter of
an amp hour of battery power per day. If you had your car
parked for two weeks at the airport, the unit would have drawn
3.2 amp hours of power during that two week period. Most
car batteries store something in excess of 50 amp hours of
charge, so the current drain by the SafeDriver is unlikely to
result in draining the battery significantly for all normal
periods of inactivity.
Accuracy of the Data Reported
The information reported by
the SafeDriver unit was close to exactly the same as the data in
the car - unsurprising because they were both using the same
'raw data' from the car's computer.
I also matched it against a
GPS unit, and again found a close match in values.
The SafeDriver slightly
under-reported on maximum speed (by perhaps 2 mph) but this is
probably due to a discrepancy between the vehicle's speed sensor
and the GPS speed calculation rather than due to any errors in
how the SafeDriver itself calculates/displays such things.
Trying to 'Cheat' the
Is it possible to cheat the
SafeDriver system and avoid its telltale monitoring? I
tested six scenarios.
First, I drove somewhere
without the receiver with me. When I returned, the
receiver downloaded the data from my travels and updated itself
with a new display of max speed, miles traveled and number of
sudden brakings. So the first strategy to avoid the
scrutiny of the SafeDriver system failed.
Second, I unplugged the
transmitter, went for a drive, then plugged the transmitter back
in again. The system couldn't then update itself with data
it had never received, but it displayed a prominent 'Tamper'
alert on the receiver's display. So the second strategy
failed to avoid the scrutiny of the system too.
I removed the battery from the Transmitter, drove somewhere,
then replaced it again. This caused the transmitter to
lose all data and reset itself, and to again display a 'Tamper'
alert. A third failure to cheat the system.
There may be other ways to
cheat the system, but they would involve major brain surgery
inside the car's computer system and cutting wires to the OBD-II
port, which was definitely not something I wanted to trial.
So it seems fair to
pronounce the system reasonably tamper-proof from most moderate
level attempts at breaking its security.
There are two more forms of
cheating that I also tested.
The first was to only very
briefly speed up to set a new maximum speed, then to immediately
reduce the speed again. This was a test to see if the unit
was sending out lots of short duration samples to accurately
depict even short maximum speeds, or if it was perhaps sending
out an average speed reading once every 30 seconds during its
regular handshake/synch between transmitter and receiver.
Using both the GPS and
speedometer to measure an instantaneous maximum speed, I got the
car briefly to a certain speed where we need not publicly
disclose the first digit, but the second digit displayed on the
GPS came to a 7.5 - think of it, perhaps, as 27.5 mph - a speed
which closely correlated with the more approximate indication on
the analog speedometer. With the GPS having a short
interval of sampling/averaging error itself, it is probably
reasonable to assume the true maximum speed briefly reached was
perhaps(2)8 or (2)9 mph.
The SafeDriver reported a
maximum speed of (2)6 mph. So there was a very slight
degree of under-reporting, but there are also very few scenarios
where even a wild and crazy teenager would roar at full throttle
up to a high speed then immediately take his (her?) foot off the
gas pedal and stomp down on the brake pedal, so this mild
under-read does not seem serious.
Further testing showed that
the SafeDriver always slightly under-reported the maximum speed
(or possibly the GPS slightly over-reports the maximum speed),
so this was hardly a successful cheat at all.
The final form of cheating
was to see what would happen if I only slowed down perhaps 12
mph rather than 15+ mph, but in a very brief interval of time so
as to be braking at a rate much harder than losing 15 mph in 2
With lovely new tires,
automatic brake assist, traction control and ABS, the Landrover
responded enthusiastically to my panic stop, and I sliced about
12 mph off the vehicle's speed in less than a second, only to
then immediately release the brake pedal and stop on the gas
again to ensure I didn't continue to inadvertently decelerate
past the magic 15 mph number that I knew would for sure trigger
a 'Sudden Brake' report on the unit.
This sort of cheat process
did work. The unit seems to simply track the speed in a
rolling two second period, and is only concerned if there is a
total reduction of 15 + mph in less than two seconds.
This is not really a
loophole. Trust me when I say it is very hard to panic
brake and 'only' lose 12 mph in the process!
So not only can one not
totally defeat the SafeDriver's reporting, one can also not skew
its reporting to make it materially under-report the driving
data it is monitoring.
There is another way to try
and cheat the system - and that would be simply to reset the
unit. However, resetting the unit requires a knowledge of
the secret passcode, and so that makes it difficult rather than
easy to reset it.
Besides which, if you did reset the
unit, two things would happen. First, you'd also be
resetting the miles traveled measure, which could cause an
obviously wrong value to be displayed there. Second, the
system actually counts the number of times it has been reset, so
that would increase the count of resets, which you may or may
not ever notice.
The password is only
semi-secret. You can download the instruction sheet for
the unit from the manufacturer's website, and both the standard
reset and the absolute master system password are both printed
on there, so a highly motivated person trying to cheat the
system could obtain both passcodes with only a small amount of
difficulty. But because the results of their resetting
would be displayed on the unit, there is still a reasonable
degree of tamper-evidence remaining.
False Tamper Indication
On one occasion during my
testing, the unit incorrectly displayed a 'Tamper' warning.
This is probably a very rare
event, but could potentially occur as a result of the car's
voltage dropping too much for too long, especially while
starting the car. So if your unit displays a Tamper
warning and your teen maintains they are guiltless, they might
be telling the truth.
There's a way of
cross-checking this - if the distance traveled reading seems
correct, then probably it is a false Tamper message rather than
a valid one, but if the distance traveled reading seems way low,
then it is a valid Tamper warning.
The manufacturer advises
that sometimes it is possible to slightly unseat the battery
when first activating the fob/receiver (you remove an insulating
strip to 'turn the battery on') and if you think this might be
causing false 'Tamper' alerts to appear, you can simply unscrew
the battery compartment, reseat the battery, and then screw it
back closed again.
The SafeDriver is a very
simple unit to install, to understand, and to use.
list price of only $69.95 and being available on
Amazon for less (currently $56.13) and with no ongoing
monthly monitoring fees, it is very affordable. While it
provides only limited monitoring, it is definitely a good value
and represents a sensible compromise between 100% realtime
monitoring at one extreme and blind trust at the other extreme.
Most of all, it introduces
an element of known accountability that may prevent your
monitored driver (most likely a teen) from driving poorly in the
first place, and surely that is the most desirable outcome of
Part 2 of a two part review of the Lemur SafeDriver system.
Please click back to part 1 for an explanation of
what the SafeDriver is, what it
does and how and why.
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30 Aug 2010, last update
28 May 2011
You may freely reproduce or distribute this article for noncommercial purposes as long as you give credit to me as original writer.