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Sunday, August 22, 2010

Review: Lemur EconoDriver

I was recently sent a Lemur EconoDriver gadget to review. It looked neat, so I agreed.

The EconoDriver is a two-part device which attaches to your car's OBD-II port. The transmitter is not much larger than the OBD plug itself, and transmits data wirelessly, over a proprietary 433MHz protocol to a large key-fob which has a reflective LCD display.

The Econodriver grabs and decodes some signals from your vehicle data bus (CAN on modern cars) such as vehicle speed and engine load, to calculate some interesting stats on your fuel usage. It can calculate trip average MPG, cost of fuel used (if the correct fuel price is input), cost of fuel wasted due to idling, average cost per mile of fuel used, and will display little leaves which is, I suppose, a way to encourage better driving.

For example, from my commute home from work the other day, the EconoDriver told me that after 19 miles, I had used $1.81 in fuel, $0.07 of which was wasted due to idling. My cost per mile was $0.09, and average fuel economy was 30.0 mpg. I was awarded 41/2 out of 5 leaves for driving style.

Overall it was, as advertised, easy to install and use. The accuracy seemed decent, the monitor's 30mpg was a little bit higher than my car's on-board calculation of 29.2 mpg. My trip was only 20 miles, so over time that difference may become much smaller.

Update: After 200 miles, the difference between my car's on-board measurement (27.1mpg) and the EconoDriver's measurement (27.4) was reduced to a mere 0.3mpg, so I attribute the difference between the two on a different averaging rate.

I did have a few minor problems. First, in my car the OBD-II port has an access door, so installing the transmitter dongle required driving with the door flopping around. I had to tape the door partly shut to keep it out of the way--not elegant.

I also discovered that if you have an OBD DTC, the EconoDriver does not seem to warn you that its accuracy may be compromised. When I pulled my intake air meter sensor connector, I got the "Check Engine" light and a DTC for the air meter, but the EconoDriver did not seem to react in any obvious way. When I asked Lemur about this I was told that the EconoDriver will reduce your green rating (leaves) if you have a DTC, but this isn't very obvious. I think a good improvement would be to flash a warning if a DTC is present.

The update rate is limited to 30s, I was told for technical reasons. This means that you can't really use this device as a driving style trainer, more of a trip monitor. I would have preferred a faster update rate so I could see what kinds of driving are better.

The leaves are supposed to coach you to drive more efficiently, but my leaf score was consistently 4 1/2 to 5 out of 5, except when I sat and idled for a few minutes. Then the score was slowly reduced. I'm not sure if the leaves are useful or not.

There is no backlight on the display fob. This is consistent with the recommendation that the monitor should not be used while the vehicle is moving--but I do, and I would like a light.

Overall, would say this is a good gadget for someone who really wants to know how much money they are spending on fuel without doing hand calculations. Perhaps someone who drives for a living and wants to track fuel costs carefully for business purposes. If I didn't have a fuel economy calculation built into my car's IP already, I would consider buying one.

  • Easy to install and use
  • Calculates fuel costs and fuel economy for you
  • Relatively inexpensive, ~$80

  • 30s update rate
  • No warning if DTC present
  • OBD port dongle may interfere with OBD port door on some vehicles
  • No method included to mount display to vehicle
  • Meaning of leaves is not clear to me
Who should consider:
  • Travelling salesman or fleet user who wants to track fuel costs carefully
  • Anyone interested in tracking their fuel economy who doesn't have an on-board fuel economy monitor
  • Scangauge II auto computer, $150 (link)

*I received no compensation for this review other than the gadget itself.


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CarCheckup records telemetry, displays charts and graphs, and also tells you why your check engine light is on (with explanations)