Toyota Prius plug in
We had the opportunity to test drive a plug-in Toyota Prius in Chicago.

The Toyota Prius is one of the most fuel-efficient mass-produced cars in existence right? That’s what I thought, until I met the plug-in Prius.

The plug-in Prius I tested came courtesy of the I-GO car-sharing service. Based in Chicago, I-GO is similar to better known car-share services like Zipcar, which provides members access to vehicles for hourly or daily rental.

Part of I-GO’s mission is to lower carbon emissions by reducing the number of vehicles on the road. To that end, much of I-GO’s fleet is composed of smaller, more efficient vehicles, though trucks and vans are also available. The plug-in Prius seems like the perfect complement to this mostly frugal fleet.

The plug-in Prius I drove was one of two recently acquired by I-GO with the help of a grant provided by Northern Illinois electric utility ComEd.

What’s a Prius PHEV?

So, what’s involved in turning a Prius into a Prius plug-in hybrid electric vehicle (PHEV)? It works like this: Take a regular Prius and add a lithium-ion (Li-Ion) battery to supplement the hybrid system’s nickel-metal hydride (Ni-MH) battery. The supplemental battery is installed in the spare-tire well, an electric plug is installed in the rear bumper, and it’s all wired into to the car’s computer. Plug the car into the wall and 5.5 hours later, the Li-Ion battery is fully charged. This is the only way the extra battery is charged; the Prius’ engine and regenerative-braking feature never charge the plug-in Li-Ion battery.

The additional battery allows the plug-in car to reach higher speeds than a conventional Prius before turning on the gas engine, thereby saving fuel. A123 Systems, the battery company that converts the Toyota Prius into a PHEV, claims the conversion nets most users better than 100 mpg for the first 30 to 40 miles of travel on a full charge, a healthy gain over the standard Prius’ already miserly combined city/highway EPA rating of 46 mpg. Note, that the installation adds 200 pounds to the weight of the stock Prius.

All Charged Up: Five Plug-ins on the Horizon
Click here to read about five plug-in hybrids that will be on sale during the next couple of years.
Want a conversion for your car? Well, you can have one, provided you have a 2004-09 Prius and $10,395 to spare. A ten-percent federal tax credit available for this conversion helps cover the tab.

So how did I-GO get cars with such advanced technology? According to Sharon Feigon, CEO of I-GO, ComEd provided the grant as part of its electric-vehicle research activities. ComEd tracks the usage of the PHEV, remotely collecting usage and power consumption data. With the data, ComEd can determine how much electric vehicles would impact the electrical “grid” (the network of wires and cables that brings power to cities).

Feeding the Grid

As rolling batteries, electric cars not only use energy, but when parked, they provide it back to the grid. With the data collected from programs like I-GO’s Prius PHEV initiative, ComEd will assess the potential for vehicle-to-grid (V2G) energy storage.

The V2G process allows electric companies to draw power stored in an electric car’s battery during periods of increased demand on the grid. Feigon explained it this way: “There’s the potential for (electric cars) to be used as a smart grid solution so they can help balance the electric load on the grid and actually reduce the long-term need for more power plants,” she said. “We’re not only providing mobility to people, but we’re also helping the grid.” In the future, I-GO hopes to acquire more PHEVs and is working with Carbon Day, a company setting up solar-powered electric-vehicle charging stations.

The Test Drive

I had the chance to test drive I-GO’s PHEV Prius on the crowded city streets of Chicago, Illinois; we never traveled faster than 30 mph. The drive itself is very smooth and quiet. A person who is accustomed to driving conventional gas-engine cars might think it’s a bit odd to push on the accelerator and start moving without feeling and hearing a rumbling engine.

2010 Toyota Prius Road Test
Click here to read our review of the 2010 Toyota Prius.
The vehicle itself looks and feels just like a standard Prius: The display screen in the center of the dashboard is the same and shows electric power flow and the state-of-charge for whichever battery is being used. However, this PHEV relies more on electricity to move the car and uses the gas engine less than a regular Prius. Below 30 mph, the engine only switches on during rapid acceleration, when using the heater, and a few other special situations. Otherwise, the car glides along silently, propelled solely by the electric motor. When the Li-Ion battery is spent, the car automatically reverts to standard hybrid mode using the Prius’ stock Ni-MH battery and gasoline engine.

One of the only problems with this conversion, however, is the fact that the battery installation leaves no space for the spare tire, so another secure location needs to be found. The car I drove had some straps to hold the tire in place on the cargo floor, and while not exactly manufacturer spec, it did the job.

PHEVs look like a logical, livable stepping stone from gas-only transportation to alternative-fuel-powered vehicles. As with any new technology, there’s a chance consumers will be wary of electric cars, and issues like limited range and charging opportunities persist. However, several major automakers are further advancing electric-vehicle technology with extended-range electric vehicles (E-REV) like the upcoming Chevrolet Volt and Fisker Karma. A factory-built Prius PHEV is also in the works for 2012.

09.10.2009