Posts Tagged ‘Automotive Engineering’

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.

Ginnie PritchettMotorists’ smart key learning curve results in risky and costly lesson

ORLANDO, Fla., (March 06, 2013) – Even as the technology, security and convenience of automobile “smart keys” evolve, AAA finds motorists are not keeping pace and are frequently outsmarted by their “smart” keys.  In 2012, AAA came to the rescue of over four million members who locked themselves out of their vehicles, a number that has dropped little in the past five years; even as use of smart keys has increased.  First available in luxury brands like BMW, Mercedes and Lexus, almost all automakers now offer the smart key  as standard or optional equipment within their fleet of vehicles. As a modern convenience, transponder fobs allow motorists to enter and start their vehicle key-free.

“Traditional car keys will likely become obsolete and be replaced by technologies offering even greater security and convenience,” said John Nielsen, AAA Director of Automotive Engineering and Repair. “Motorists will need to adapt with the technology to avoid the hassle and expense of smart key replacements.”

While new smart key features provide long list of conveniences, including remote start and stored driver profiles, motorists unfamiliar with operating keyless fobs can face risky situations and lockouts. Forgetting to turn off the car before exiting the vehicle, or not knowing how to quickly shut down the engine in an emergency, has proven to be a problem for some. And, for those systems with remote start capability, it is critical that motorists never start the vehicle in an enclosed space where engine exhaust gasses containing poisonous carbon monoxide can be trapped – with potentially fatal consequences.

Just as motorists adjust to smart key features, they may be surprised to learn that smartphones may soon be an option to replace their car key altogether. Electric vehicles from Chevrolet and Nissan today have special mobile apps that can be used to monitor and control many of their basic functions.  And, Hyundai recently unveiled a more advanced concept that allows motorists to enter and start a vehicle using a specially-configured smartphone that can then interface with the vehicle to provide additional functions and services. Some of this technology could be seen in vehicles as soon as 2015.

The greater conveniences and features of modern car keys do not come cheap and require more maintenance. The purchase price of vehicles that offer modern key technology are higher, the fob battery must be changed periodically and it can cost hundreds of dollars to buy, cut and program a new or replacement key.

“The cost to replace a transponder key runs around $100, and replacement smart keys can cost several hundred dollars depending on the make and model,” continued Nielsen. “Many newer keys must be programmed by a dealer or locksmith with special electronic equipment and accesses to highly confidential codes that are required to service the vehicle security system.

AAA recommends motorists take special care of their transponder and smart keys. Here are some steps that can help prevent danger, loss or damage of vehicle keys, and limit the replacement cost in the event a key is misplaced:

  • Familiarize yourself with the full capability of your smart key and know what to do in an emergency situation
  • Become comfortable with the features of the smart key in a safe environment
  • To avoid keyless-entry remote or smart key failure, replace the key/fob battery every 2 years or when recommended by the vehicle manufacturer or the in-car low battery warning system.
  • Don’t expose your keyless-entry remote or smart key to harsh elements – especially water.
  • Obtain a spare key and store it in a safe location for emergency use only.


ORLANDO, Fla., (January 25, 2013) –  A survey by AAA has found that newer cars with built-in maintenance reminder systems are allowing owners to spend less time worrying about when to service their vehicles and more time enjoying vehicle ownership.  According to the survey, 63 percent of motorists drive vehicles with a built-in maintenance reminder system that alerts them when it’s time to have service work performed. More than half (51 percent) of those drivers rely solely on the reminder system and have maintenance done only when the system says it’s due.  AAA recommends that motorists always follow automakers’ maintenance recommendations as found in vehicle owners’ manuals, including the use of in-vehicle maintenance reminder systems (where equipped) as an accurate indicator of when a car needs service.

“It’s encouraging to see motorists accepting this technology. Maintenance reminder systems make vehicle ownership easier, and having required services performed at the appropriate intervals results in better overall performance and longer vehicle life, “ says John Nielsen, AAA’s director of Automotive Engineering and Repair. “Reminder systems can also save money by helping drivers avoid unnecessary service work.”

Reminder Systems and Vehicle Maintenance

Unlike traditional maintenance schedules based on time and/or mileage, maintenance reminder systems use various sensors and a computer algorithm to monitor vehicle operation and determine engine oil life based on real world use. The factors considered vary by reminder system, but commonly monitored values include hours of operation, engine rpm, cold starts, outside air temperature, vehicle speed and more. This analysis of real-time vehicle operating conditions makes choosing an oil change interval based on traditional “normal” or “severe service” driving conditions obsolete.

Frequency of Scheduled Maintenance

Motorists who follow their in-car reminder systems may also see a change in the frequency of recommended oil changes. While older vehicles sometimes required oil changes as often as every 3,000 miles, advancements in engine and lubricant technology have extended oil change intervals to 5,000 miles or more on most newer cars. In some cases, engines that use synthetic or semi-synthetic oils can have oil change intervals of more than 10,000 miles! AAA survey data show today’s motorists are beginning to accept longer oil change intervals, with 48 percent of drivers changing their oil every 3,000-6,000 miles.

Not All Oils Are the Same

While maintenance reminder systems typically call for extended oil change intervals, those recommendations are based on an assumption that the oil used in the engine meets the automaker’s specifications. AAA found that nearly 75 percent of motorists whose cars have built-in maintenance reminder systems understand that the accuracy of those systems depend on using engine oil that meets the vehicle manufacturer’s specifications.

Many newer cars today require the use of semi-synthetic oil (a blend of conventional and full-synthetic stocks) to maintain the warranty and ensure proper engine protection between oil changes. The use of full-synthetic oils is very common in European imports, high-performance models and engines equipped with turbochargers or superchargers. Using a lower quality oil than required will compromise engine protection, decrease the accuracy of the maintenance reminder system and potentially void the engine warranty. It is important that motorists and service providers be aware of the relevant standards for each vehicle and only use engine oils that meet them.

AAA Recommendations

AAA advises motorists to follow their vehicle manufacturer’s recommended maintenance schedule and, if their vehicle is equipped with a maintenance reminder system, to perform necessary maintenance when prompted by the vehicle. Ignoring maintenance reminders can increase vehicle wear and tear and potentially cause long-term damage. It is also important to know what type oil your vehicle requires and ensure that your service facility uses an appropriate product. The wrong oil could void a vehicle’s warranty, leaving the motorist to pay any needed repair bills.

As North America’s largest motoring and leisure travel organization, AAA provides more than 53 million members with travel, insurance, financial and automotive-related services. Since its founding in 1902, the not-for-profit, fully tax-paying AAA has been a leader and advocate for the safety and security of all travelers. AAA clubs can be visited on the Internet at AAA.com.

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