The computers in all modern automobiles monitor our vehicles' inner workings, and now Dodge is putting its microprocessors to work for the benefit of muscle-car enthusiasts. The 2013 Challenger SRT's in-car apps, called Performance Pages, can look deep into the car's driving data and pull out information about 0-60 acceleration, braking distances, G-force loading, and more.
The apps yield fascinating data, so we recently used the Challenger SRT to teach some kids at a local high school a thing or two about physics. See? Maybe doing burnouts and driving donuts can have practical applications after all.
The Performance Pages apps are available through the instrument cluster. Other performance cars that offer track apps include the Ford Mustang, whose selection resembles the Challenger's but adds a stoplight countdown for a 0-60 test. The BMW M Laptimer is a smartphone app that syncs with the car, and can show your exact speed around corners, where you pushed the throttle and backed off, how many G-Forces you pulled, and even lap times.
Cars' internal computers have gathered the data used by these apps for many years, and mechanics and racers have tapped into this information for just about as long. But Dodge's SRT Performance Pages are an example of a more mainstream use of the data, and we expect to see more apps, revealing more secrets, in the very near future.
Here's how to squeal tires in the name of science (with permission from the school where we did our testing, of course): Take a parking lot that runs about a football field in length and ends in a grassy knoll (not that grassy knoll). Spread liberally with orange traffic cones. Arrange students carefully behind the growling car and its 6.4-liter, V-8 engine. Then fire up the apps and drive.
Going 0-60 for educational purposes
To use the Performance Pages, I pressed the menu button on the steering wheel, then the up arrow to find the Performance Features section. I pressed up to see the first 0-60 test. Accessing these tools could not be any easier--you can punch them up quickly and start racing. (On the Charger and the Chrysler 300, the exact same tools are available in the touchscreen. They look better, but they're easier to use on the cluster.)
I started with a 0-60 acceleration test. My friends placed cones down a corridor in the lot.
The 0-60 test uses the same sensors that look for tire spin and control the antilock braking system, so it knows when you are at zero. To start the test, I came to a complete stop in front of the first cone. The cluster said "Ready," and I shifted into first and took off. The tire sensors measure tire speed and distance until you hit 60 mph.
The tires squealed, and the dial started counting the seconds. After a few tests, I ended up clocking a score of 4.04 seconds. That's fast! Actually, it's too fast. Dodge engineers told me that time resulted from way too much tire spin.
The fix? Launch mode. To use it, I pressed the traction control button once (to disable traction) and then a second time (to enable launch control). I pressed down on the clutch, then down on the accelerator, and finally released the clutch to launch. Using this method, the tires didn't spin nearly as much. I clocked a more reasonable time of 5.5 seconds. The app automatically saves the best time unless I do a reset.
So, where does physics come into play? The test is accurate within one-tenth of a second. You're not measuring the inertia or movement of the car, but your ability to clock the fastest time based on tire spin. It's fun, but not designed to work like a drag racing speed track. (A simple method to track actual movement: Use an iPad app like Mobile Science Acceleration.)
As an extra perk, the Performance Pages let you tweak the rpm setting for launch mode--say, 4500 rpm at the high end for a jack-rabbit start, or down to 2500 rpm for a smoother launch on a looser road. You just scroll to the 'RPM' setting and change it with the arrow keys.
Next, I tried the braking test. I clicked up on the arrow key. After hitting 30 mph, the display showed "Ready" to tell me when to brake. I accelerated a bit more and then hit the brakes, firmly but not abruptly. After stopping, the display read 72 feet. Not bad. Performance braking is all about car control, and the Challenger worked famously.
My most interesting physics lesson came with the G-force test, where the app measures the force of acceleration, braking, and left and right cornering. G-force is actually a measure of force on a human body: One G equals 9.8 meters of gravitational force per second squared, at sea level. Now we'd see how much the car could withstand.
After clicking up on the arrow again, I saw the G-force display. It looks like a magic quadrant: four radars with numbers that show the level of force at all times as you drive. (You can also click up once more to see the "peak" G-force ratings, saved until you do a reset, as in the other tests.) In the parking lot, I tried accelerating quickly (clocking 0.96 of G-force), braking quickly (0.65 G-force), and doing some quick corners (peaking at 0.92 G-force).
Aiming for 1.0 G-force, perhaps with puking
But I wasn't satisfied. I wanted to hit at least 1.0 G-force. So, I had my friends make a 300-foot cone circle. I piled a few of the students into the back of the car. Then I tried to make them puke.
We started going about 20 mph, increasing the speed steadily. There's no magic to the 300-foot-diameter (or 25-foot radius) circle in terms of physics, but it's just about right for holding a corner tight and accelerating. The students screamed. No one puked. But we did manage to hit almost 1G--about 0.98 on the right side of the car. Success!
What's most surprising about the G-force testing in the Challenger is the role of the sway bar in the front and aft that controls the suspension. The bar keeps all four tires planted, helps you maintain full control, and avoids the jarring sensation around a tight corner. It feels like the car has adjusted itself to help you stay flat on the road, and it's a pure joy to experience.
"The sway bar is actually pushing up on the inside tire, which is resisting the left side of the body to roll, and at the same time is pushing up on the right side, tire which in turn is keeping the right side of the body from raising up," says Jim Wilder, the product manager for the Dodge Challenger. "By doing this it flattens the body motion out while cornering."
And that's our lesson for today, kids. What did we learn? That in the highly unlikely event that you can convince your parents to buy you a $38,995 2013 Dodge Challenger SRT, you can tell them that the Performance Pages apps will help you do better in physics. Right. I don't think I could get that past my spouse, either, if that's any consolation.
More seriously, the growth of apps that can look deep into a car is changing how we relate to our vehicles. Cars are no longer mute and mysterious mobility machines. They can talk to us. What we're waiting for now is the ability to talk back.
Note: Dodge recently rolled out the 2014 Challenger, where the Performance Pages work exactly the same.