Teacher:In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
Teacher: Now, understand the problem? Solve this instance: Does it pay to pay for premium gasoline? 
  
 Travel and leisure company AAA says it does not — and that U.S. drivers waste $2.1 billion in the past 12 months by paying for premium gas when the regular kind would do just was well. 
  
 For years, energy companies have tuned their marketing to the belief that, either occasionally or frequently, springing for the pricier stuff at the pump will be a treat for your car — a cleanse of sorts, or perhaps a performance boost that saves money in the long run. 
  
 For cars designed to run on regular gasoline, AAA could find no difference between premium and regular in terms of horsepower, fuel economy, or lower tailpipe emissions. 
  
 “Motorists are not treating their vehicle in any meaningful way” by using premium gas when the vehicle is designed to run on regular, AAA said in a research paper released Tuesday. 
  
 According to the Energy Information Administration, the share of premium gas in total gas sales has steadily increased to 11% in August and September 2015, the highest in more than a decade. 
  
 The rising demand is likely driven by changes in fuel requirements for light-duty vehicles in response to fuel economy standards, although lower gasoline prices are also supporting the increase for that market, the EIA said in April. 
  
 Premium gasoline is gasoline with a higher octane rating — and a fuel with a higher octane level is less prone to cause engine “knocking,” which can damage engines. If nobody talks about “engine knocking” anymore, it is because of octane, which is basically a gasoline additive. 
  
 As a gasoline component, octane has taken many forms through the years, including lead (phased out for health and environmental reasons in the 1970s) and most recently ethanol. At the pump, regular gasoline will have a minimum octane rating of 87, then 89 for the mid-grade, and 91/93 for premium. 
  
 While most car engines are built to run on regular gasoline (AAA said that only 16% of vehicles sold in the U.S. require premium fuel), some car makers require or recommend the higher-octane, pricier versions most to meet promised power output and fuel economy figures. 
  
 That has led to the belief that premium blends — which on average cost 23% more than regular gasoline, AAA said — equal better-run cars, regardless of model or maker. 
  
 Energy companies have capitalized on that belief, with “marketing campaigns that tout the cleaning abilities of their fuel detergent additive packages,” AAA said. 
  
 To run its tests, AAA chose three vehicles — a Toyota Motor Co. 7203, +0.65% Tundra pickup, the Fiat Chrysler Automobiles FCA, +1.67% full-size sedan Dodge Charger, and a Mazda Motor Corp. 7261, -0.36% compact Mazda 3. 
  
 Want a real treat for your car? AAA says don’t miss scheduled maintenance and maybe skip the no-name gas station with that enticing low price. 
  
 Earlier this year, AAA released a study that claims to have found “significant differences” in the quality of gasoline sold in the U.S., with those meeting a standard called Top Tier performing the best and leaving less residue on engines. 
  
 A list of gasoline retailers selling gasoline that meets the standard can be found here. ||||| Americans wasted over $2 billion last year putting expensive premium gasoline into cars that don't need it, the automobile ownership group AAA said Tuesday. 
  
 Most car engines in America are designed to run on regular gasoline and, despite the superior-sounding name, premium gasoline provides no benefit over cheaper regular gasoline in those engines. 
  
 Premium has a higher octane rating than regular gas. That means it's able to tolerate higher pressures inside the engine. Engines designed to run on regular don't operate at pressures high enough to require the extra octane, so putting premium fuel into an engine that doesn't require it is simply a waste of money, AAA said. 
  
 "Drivers see the 'premium' name at the pump and may assume the fuel is better for their vehicle," said John Nielsen, AAA's managing director of Automotive Engineering and Repair. "AAA cautions drivers that premium gasoline is higher octane, not higher quality, and urges drivers to follow the owner's manual recommendations for their vehicle's fuel." 
  
 About 70% of vehicles now on the road require only regular fuel, AAA said. Still, about 16.5 million drivers unnecessarily filled up with premium at least once last year, according to AAA. That means Americans spent more $2.1 billion on more expensive fuel for no reason, the group calculated. 
  
 On average, premium costs about 50 cents a gallon more than regular, AAA said. 
  
 Related: World's fastest VW Beetle goes 205 MPH 
  
 About 16% of Americans drive vehicles that actually do require premium fuel, though. These are mostly high-performance or luxury models. Using cheaper regular fuel in these engines can cause damage 
  
 In tests conducted along with the Automobile Club of Southern California's Automotive Research Center, AAA ran regular and premium fuels in various different car engines designed to run on regular. Using premium fuels in these engines did not produce more horsepower, better fuel economy or lower tailpipe emissions. 
  
 In some vehicles, premium fuel is "recommended" but not required. Those vehicles may operate with lower power or efficiency using regular fuel. 
  
 Still, it may not hurt the engine to use regular in these vehicles provided that no engine "knock" is heard, AAA said. If an unusual knocking or banging sound is heard from the engine, as it might be under particularly heavy use, premium fuel should be added to the tank as soon as possible, Greg Brannon, AAA's head of Automotive Engineering, said. 
  
 As always, he said, drivers should consult their owner's manual about which type of fuel is best. 
  
 Photos: Coolest cars for $18,000 
  
 A separate AAA study released earlier this year showed that cheaper off-brand gasolines can harm engine performance in the long term. This is a separate distinction from premium vs. regular gasoline, though. In that study, AAA was comparing gasoline sold by different retailers. 
  
 AAA found that gasolines sold by "no-name" gas stations -- ones that weren't selling a major brand like Exxon Mobil, BP, Shell or Chevron -- could cause serious build-ups of engine deposits over just a few thousand miles. 
  
 "Such carbon deposits are known to reduce fuel economy, increase emissions and negatively impact vehicle performance, particularly on newer vehicles," AAA said. 
  
 This can happen because the cheaper brands of gasoline may not use engine-cleaning detergent additives found in major name-brand gasolines. 
  
 Editor's note: Correcting typo in Greg Bannon's name. ||||| Smarter Engines Protect Themselves 
  
 If you're still in doubt about switching to a lower-octane fuel, here's a more in-depth explanation of why the change is unlikely to hurt your car: 
  
 First of all, premium gas has a higher octane rating, an important factor in helping prevent engine knock or "pinging." Depending on where you live, this premium-grade fuel could be 90 octane, 91 octane, or even 94 octane. 
  
 That's one reason premium costs more. To increase the octane rating and reduce knock, refineries use a more elaborate process that blends an expensive substance called alkylate into the fuel. 
  
 What is engine knock? After vaporized fuel mixes with air and fills the combustion chamber, rising pistons compress it. The spark plug then fires, initiating the combustion process. But combustion doesn't happen instantaneously. It takes some time for the flame kernel to develop, grow and then burn the entire contents of the fuel-air mixture in the cylinders. There's a critical period in the middle of this process when the mixture in the unburned region is being heated by the neighboring burned gas while being compressed by the rising piston. 
  
 This one-two punch can cause the mixture in the unburned region to self-combust rapidly in an uncontrolled fashion. That's the knock, which hurts power and can damage the engine. Simply put, high-octane gasoline can be compressed and heated to a greater degree without self-igniting. That's why high-performance engines use premium fuel. 
  
 In the old days, engines could not deal with fuels of varying octane ratings. Using the wrong fuel would make the engine knock and possibly damage internal engine components. But today, engine control systems can compensate for low octane by adjusting ignition timing to avoid knocking. This sophisticated electronic capability effectively tunes engines on the fly and gives drivers more flexibility in the grade of fuel that they can use safely. 
  
 Compared to premium gas, lower-octane fuels don't allow the engine to run as much ignition advance during situations calling for rapid acceleration. More ignition advance causes spark plugs to fire sooner, which (within limits) allows the engine to make more power — and accelerate more quickly — under these conditions. Since the engine doesn't make quite as much power with low-octane fuels, this translates into slower acceleration in cars for which premium fuel is recommended. The performance loss is especially noticeable in turbocharged gasoline engines, which have become increasingly popular in recent years. 
  
 The performance loss, however, is something you will only notice if you have a heavy foot and accelerate rapidly from a dead stop or when you change lanes at highway speeds. But if you accelerate moderately, the loss of power may not be noticeable whether you use premium or regular-grade fuel. |||||
Student:
It may make you feel posh (or practical) to pull up to the pump and request premium unleaded for your tank, but chances are you're throwing away your hard-earned cash on an unnecessary type of gas. Per the American Automobile Association, US drivers blew about $2.1 billion on higher-octane fuel than their cars need, as most engines—about 70%—are sated with regular unleaded fuel, CNNMoney reports. AAA says despite this fact, about 16.5 million drivers admitted filling up at least once last year with the higher-grade gas, which costs, on average, about 50 cents more per gallon than regular. "Drivers see the 'premium' name at the pump and may assume the fuel is better for their vehicle," an AAA engineering and repair expert notes. High-octane fuel's benefits, per Edmunds.com: It's able to withstand more compression without combusting, making it critical in high-performance engines. But while cars on the "premium required" list need that higher-grade fuel to prevent engine damage—about 16% of Americans drive those types of cars, per CNN—Edmunds notes cars on the "premium recommended" list are likely just fine with regular gas, thanks to advanced engine technology. The engine won't suffer, and the worst effect may be a slight speed reduction (e.g., a half-second when going from zero to 60mph). And while some drivers may still buy premium once in a while to flush out the tank, experts note all gas grades have an ample amount of additives for cutting down emissions and keeping engines in tiptop shape. What AAA says is a better bet, per MarketWatch: taking your car for regular maintenance checkups and keeping away from low-quality gas, which is different than regular gas from a top-tier brand. (The Southeast is enduring a gas-price spike.)