10 Diagnostic Apps and Devices to Make You a Better Driver

10 Diagnostic Apps and Devices to Make You a Better Driver
Your car can tell you what it's up to under the hood—you just need the right tools to understand what it's saying. Hardwire yourself into the brains of your car with these 10 OBD-II apps and devices.

Since 1996, cars sold in the U.S. have been required to provide a connection for mechanics and inspectors to measure what's going on electronically under the hood. The system, called On-Board Diagnostics generation two (OBD-II), uses a 16-pin connector mounted somewhere near the instrument panel to gather information. If it detects faults, it transmits them in four-digit codes in four categories: P for powertrain, U for computer, C for chassis, and B for body.

That's great if you want to know why your Check Engine light is on. But how does this translate into having a little fun behind the wheel? Over the past half decade, there's been an explosion of aftermarket gadgets that allow the OBD-II connection to transmit useful stats, such as instant fuel economy, engine speed, temperature, and vehicle speed. Couple this valuable info with the accelerometers and GPS locating ability of common smartphones, and you can get a sophisticated view of your car's performance, efficency, and even your own driving prowess. Here are 10 of our favorite apps and devices for performance driving.



DevToaster's Rev
Price: $39.95 (requires additional OBD-II transmitter, about $150)

The coolest thing about the DevToaster Rev iPhone and OBD-II system, which won a Popular Mechanics Editor's Choice Award in 2009, is that it can tell you exactly how you're driving and how your car is behaving on a specific map. It will display how quickly or how efficiently you travel a challenging road by showing a graph of acceleration and braking forces, including lateral acceleration (g-forces). It's like having a driving instructor and vehicle performance measurement equipment along for every ride.

To start, you buy a wireless OBD-II data transmitter about the size of a matchbox and plug it into your car's OBD-II port. Then download the Rev application to your iPhone and you're ready. In addition to monitoring and graphing your performance behind the wheel, the Rev application also alerts you to problems and wear with your car, and a recently added feature allows you to reset your Check Engine warning light. Rev will also log your data so you can compare different trips in different cars, or check to see if the new intake or exhaust systems you just bolted on actually improves your performance.
PLX Kiwi Drive Green
Price: $199.95

The PLX Kiwi Drive Green is an efficiency driving coach that uses a stand-alone display and plugs into your car's OBD-II port using a cord. The device opens up a large menu of efficiency coaches, including a "Kiwi Score" game that tests your ability to get the best fuel economy possible. We gave the Kiwi Drive Green a Popular Mechanics Editors Choice Award back in 2008 for its forward-thinking approach. The Kiwi also measures fuel economy on separate trips, as well as how much fuel costs on each trip.
PLX Kiwi MPG
Price: $89.95

The PLX Kiwi MPG packs some of the same functions as the Kiwi Drive Green, but those mileage readings appear on much smaller digital display. It's a lot less expensive than the Drive Green, but you don't get the efficiency driving coach here. However, if your car didn't come with a trip computer or an instantaneous fuel-economy readout, then PLX Kiwi MPG will add those functions in a tiny unit that you can mount right on your instrument panel.
PLX Kiwi WiFi/Bluetooth
Price: $149.95/$99.95

These two OBD-II devices from PLX allow you to wirelessly connect to your car's computer with your iPhone, iPod Touch, or Android smartphone. The system lets you read engine and vehicle diagnostic codes through a free app. Like the DevToaster Rev, these devices let you track your car's performance over a particular course via GPS, and the faster connection of the iPhone WiFi model can even calculate lateral g-forces.


Car MD
Price: $70

The Car MD won't turn off your Check Engine light, but this easy-to-use gadget will find out which trouble code is making it illuminate and then take you to a website that explains the problem under the hood in plain English and suggests solutions specific to your vehicle. In addition, the software connects you to an online calculator that estimates the price of the repair. You can take the estimate to a repair shop to confirm the price.


GoPoint Technology GL1 Cable
Price: $99

This do-it-all OBD-II device won one of our Breakthrough Awards in 2010. The GoPoint connects with an iPhone or iPod Touch through a hardwired cable. (Some car enthusiasts prefer an old-school wired connection to eliminate possible interference or data-speed issues.) A similar app called BL1 uses a supplied Bluetooth transmitter for the same price. In addition to diagnosing faults and resetting the Check Engine light, the GoPoint GL1 provides a simple explanation to fault codes and displays real-time data on small graphics windows.


VoyagerDash
Price: $1.00 (also requires OBD-II Bluetooth adapter for Android phone, about $20 to $100)

The VoyagerDash is an Android app that, using a Bluetooth transmitter from the OBD-II port on your car, sends data to your smartphone. Then simply mount the phone on your car's dashboard and you can see either gauges that display your car's performance or bar graphs that show a record of performance over time. This application also lets you read trouble codes stored in the car's computer, though there is no function to reset the codes.



































OBDroid
Price: $2.99 (requires an OBD-II Bluetooth transmitter, about $20 to $100)

The OBDroid, coupled with a Bluetooth connection to your car's OBD-II interface, is a fault-code reader that describes what the codes mean on an Android smartphone. It also displayd vehicle and engine speeds and intake airflow. And yes, it calculates fuel economy and resets Check Engine warning lights, too.



alOBD ScanGenPro
Price: $4.99 (requires an OBD-II Bluetooth transmitter, about $20 to $100)

This ungainly named app is preprogrammed with descriptions of error codes. The alOBD ScanGenPro displays real-time status of some sensor data in a digital format as well as a graph. It also stores and exports fault codes as well as specific vehicle parameters that are proprietary to some car manufacturers. And best of all, the alOBD can be customized for specific data captures.


Torque
Price: $4.95 (requires an OBD-II Bluetooth transmitter, about $20 to $100)

Torque. It's a very simple name for an app with quite a lot of capability. And it's been gaining popularity amongst car enthusiasts who own Android devices because it uses both Google Earth real-time car-performance displays and a calculated horsepower and torque measurement. Most important, it automatically records 0 to 60 mph sprints. Like diagnostic-only OBD-II devices, it also retrieves and resets fault codes, which is certainly helpful if you've modified your car.