Premium is the highest octane fuel you can buy and has levels of 91-94. Although some companies market their different grades of gas under names such as “Super Premium”, Ultra or “Ultimate”, they all refer to the octane rating of gasoline. The answer to two of the questions is diesel. Diesel fuel produces lower emissions and lower toxic emissions. In addition, diesel engines save more fuel.
As to why there is a discrepancy, there are probably a variety of factors. Mobil, which dates back to the mid-1980s, is one of the best-known names when it comes to quality gasoline. In 1999, they merged with Exxon to form Exxon Mobile, making it one of the largest oil companies in the world. When using a lower fuel grade than recommended or required, the ECU (electronic control unit) of a modern vehicle can take into account the different octane levels and adjust accordingly.
For most vehicles, higher octane fuel can improve performance and fuel consumption and reduce carbon dioxide (CO) emissions by a small percentage during severe service operations, such as towing a trailer or hauling heavy loads, especially in hot climates. Gasoline is the most common fuel for cars and is used worldwide to power cars, motorcycles, scooters, boats, lawn mowers, and other machinery. By breaking down hydrocarbons found in waste fuel oil into smaller components, refineries can produce gasoline. Therefore, unless you have an older vehicle with a carbureted engine, you should use the manufacturer's recommended fuel for your vehicle, even when 85 octane fuel is available.
Basic knowledge of fuel types and grades is useful to any driver and will help you make decisions that will improve the operation of your car. Many newer vehicles can adjust spark timing to reduce shock, but engine power and fuel economy will continue to suffer. Diesel fuel is also manufactured from petroleum, but it is refined using a different method than that used to create gasoline. To keep things simple for consumers, when a participating retailer sells Top Tier fuel, all octane grades, from regular to premium gasoline and diesel, must meet higher-level standards.
In most cases, the Premium label means that the fuel has a higher octane rating, which is a number that measures its performance. Diesel emissions are different from gasoline emissions because the two fuels are made of different hydrocarbons. If your owner's manual says your vehicle doesn't require a premium, but it says your vehicle will perform better with higher octane fuel, it's up to you. Cars with a diesel engine generally achieve better fuel efficiency or fuel efficiency than vehicles that run on gasoline.
However, the diesel engine travels much further with a gallon of fuel than a comparably sized gasoline engine. Engines with a high compression ratio generally require higher octane fuel to achieve the desired level of performance, fuel efficiency and emissions. SUVs and sports cars perform best in Plus or Premium (higher octane), as their engines produce more fuel compression for better driving.