Posts Tagged ‘Reid Vapor Pressure’

Now in development, vehicle-to-vehicle (V2V) communication systems use a GPS receiver, a radio/antenna and a computer to share automobile location and movement information with other V2V-equipped vehicles up to a quarter mile away. That information is then analyzed and used to alert the driver to potentially hazardous situations. Warnings can be provided in a variety of ways, including sounds, visual icons, control feedback and seat vibrations.

More advanced systems may also employ vehicle-to-infrastructure (V2I) communications that allow the car to receive driving condition information from traffic lights, road signs or even the highway itself. Common notifications might include traffic congestion, speed limits, or height restrictions on bridges and tunnels. The combination of V2V and V2XI technology is often referred to as V2X.

When V2X capabilities are integrated with advanced driver assistance systems, the vehicle could take control of the brakes and/or steering to avoid a collision if a driver fails to react in time. Unexpected emergency situations combined with ineffective driver reactions result in millions of crashes every year. The National Highway Traffic Safety Administration projects that V2X systems could help prevent up to 81 percent of collisions involving drivers not impaired by drugs or alcohol. As V2X-equipped vehicles begin to appear on our roadways, shared information could also be used to smooth traffic flow, reduce congestion, improve fuel economy and cut emissions.

Automakers, technology providers, research institutes and governmental agencies are all engaged in developing V2V and V2I technology. The Department of Transportation is expected to decide some time in 2013 whether V2X systems should be among the safety features built into our vehicles. Given its potential benefits, there is a good possibility your next new car will employ V2X communications to help you be a better driver.

Gasoline or Compressed Natural Gas?

June 10th, 2013 by AAA

Consumers face competing priorities in making automotive decisions. They want to save money on fuel, and they appreciate protecting the environment by reducing greenhouse gases, but their primary concerns are most often cost and convenience. An example is the use of compressed natural gas (CNG) as an automotive fuel, which offers both advantages and challenges.

An August 2012 AAA study found 39 percent of AAA members were interested in vehicles that used two or more fuel sources, such as gasoline-electric hybrids or “bi-fuel” vehicles such as those that can run on either gasoline or CNG. However, trade-offs that include higher vehicle prices and limited refueling options are holding them back.

“Consumers want to make the right decision for the environment, but they also need that decision to be economically sound,” says AAA’s Managing Director of Automotive Engineering and Repair John Nielson. “Vehicles powered by alternative fuels such as CNG have the potential to meet those requirements, but the extent of the benefits varies with the vehicle and how it is used.”

CNG is up to 40 percent less expensive than gasoline for the equivalent amount of energy. On the other hand, converting a vehicle to run on CNG can cost $10,000 or more, an expense that can take years to recover in fuel savings. CNG fueling stations are also rare in most areas and unavailable in others. The Department of Energy says there are just 578 public CNG fueling stations in the U.S.

Most CNG vehicles on the road today are large trucks that get relatively poor fuel economy and travel tens of thousands of miles per year. Under these conditions, the time needed to recover the higher price of a CNG vehicle can be as little as two years, with ongoing fuel cost savings thereafter. As a result, most current CNG vehicles operate in commercial service, and large fleets often install a private CNG fueling station to meet their vehicle fueling needs.

The only CNG vehicle currently targeted at the average motorists is the Honda Civic Natural Gas – a dedicated CNG vehicle with no provision to use gasoline as a backup. With a list price of $26,465, the Natural Gas costs $5650 more than a comparable gasoline-powered Civic. In addition, the lower energy content of CNG combined with limited storage tank space gives the Civic Natural Gas a driving range of just 190 miles versus nearly 400 miles for a gasoline Civic.

“CNG vehicles can make sense and save money in some commercial applications,” says Nielsen. “However, for the average consumer, the added cost and greater inconvenience of using CNG to power a passenger car doesn’t pencil out right now – although that could change in the future.”

Every spring gas prices seem to skyrocket to the highest prices of the year. Why does this happen? In explanation, we hear the experts say that many of the refineries are “down for maintenance while transitioning from winter-blend to summer-blend gasoline,” but what does this mean?

The difference between summer- and winter-blend gasoline involves the Reid Vapor Pressure (RVP) of the fuel. RVP is a measure of how easily the fuel evaporates at a given temperature. The more volatile a gasoline (higher RVP), the easier it evaporates.

Winter-blend fuel has a higher RVP because the fuel must be able to evaporate at low temperatures for the engine to operate properly, especially when the engine is cold. If the RVP is too low on a frigid day, the vehicle will be hard to start and once started, will run rough.

Summer-blend gasoline has a lower RVP to prevent excessive evaporation when outside temperatures rise. Reducing the volatility of summer gas decreases emissions that can contribute to unhealthy ozone and smog levels. A lower RVP also helps prevent drivability problems such as vapor lock on hot days, especially in older vehicles.

The US Environmental Protection Agency (EPA) says conventional summer-blend gasoline contains 1.7 percent more energy than winter-blend gas, which is one reason why gas mileage is slightly better in the summer. However, the summer-blend is also more expensive to produce, and that cost is passed on to the motorist.

The switch between the two fuels happens twice a year, once in the fall (to winter-blend) and again in the spring (to summer-blend). The changeover requires significant work at refineries, so oil companies schedule their maintenance for those times when they will already be “down” for the blend switches.

As a consumer, the main thing to understand is that there are real reasons for the switch from winter- to summer-blend fuel, even if it results in some pain at the pump.



YouTube Videos

AAA Senior Driver Expos

NewsRoom Video Gallery

Media: Find and Download AAA Videos and B Roll.