The constant fluctuation in fuel prices puts owners of flex-fuel vehicles facing a recurring dilemma every time they fill up. The decision between alcohol and gasoline, which directly affects the monthly budget, requires more than a simple look at the values displayed at the pump. Fatores such as engine efficiency, the type of route traveled and even the composition of the fuel are crucial for a truly economical choice.
As automotive technology has evolved, the old “70% rule” that for years served as a quick guide for drivers has become an inaccurate method. Modern engines are designed to extract greater efficiency from both fuels, changing the efficiency ratio that was previously considered standard. Além Furthermore, changes in the composition of gasoline, such as the increase in the mixture of anhydrous ethanol, also directly impact its performance and consumption.
Given this scenario, carrying out a personalized calculation for your own vehicle is no longer an option and has become a necessity for those looking to optimize expenses. Entender your car’s specific consumption of each fuel is the only way to ensure that the decision made at the station is, in fact, the most financially advantageous.
How to calculate real consumption
The first step towards an informed decision is to accurately determine your vehicle’s consumption. For more recent models, the on-board computer offers this information in a practical way, displaying the kilometers traveled per liter (km/l) in real time or as an average. Essa tool is an excellent starting point, but for further analysis, manual calculation remains the most reliable and accurate method.
To perform manual measurement, start by filling the tank completely with one of the fuels, be it ethanol or gasoline, until the pump automatically disarms. Zere the vehicle’s trip meter and use it normally, on your usual routes, until it is necessary to refuel. On the next refueling, fill the tank again until automatic disarming, using the same fuel. Anote the number of liters that were added and the mileage recorded on the trip meter. The formula is simple: divide the total kilometers driven by the number of liters filled. The result will be the average consumption in km/l for that fuel. Repita the entire process with the other fuel to have a solid basis for comparison.
The obsolescence of the 70% rule
The famous “70% rule” emerged along with the first flex cars on the Brazilian market, in the early 2000s. The logic was simple: if the price of a liter of ethanol was higher than 70% of the price of a liter of gasoline, it would not be economically advantageous. Contudo, this reference is outdated. Flex engines have evolved significantly, with more sophisticated electronic injection systems, higher precision sensors and variable compression ratios that optimize the burning of both fuels. In many modern vehicles, ethanol efficiency can reach 75% or even 80% of gasoline efficiency, which completely invalidates the old fixed calculation. Ignorar this technological evolution means, in practice, leaving money on the table when making a decision based on a premise that no longer reflects the mechanical reality of current cars.
Finding the Ideal Ratio for Your Vehicle
With the consumption data in hand, the next step is to find the exact proportion for your car. Para this, divide the average consumption obtained with ethanol by the average consumption recorded with gasoline. The result of this calculation will be your personal “equivalence rate”.
For example, if your vehicle does 8.5 km/l with ethanol and 11.5 km/l with gasoline, the calculation would be: 8.5 ÷ 11.5 = 0.739. Arredondando, the proportion for your car is 0.74, or 74%. Isso means that ethanol will be the most economical option whenever the price of a liter is up to 74% of the price of a liter of gasoline.
With this rate in hand, the decision at the gas station becomes simple mathematics. Basta divide the price of a liter of ethanol by the price of a liter of gasoline. If the result is lower than your equivalence rate (in the example, 0.74), fill up with ethanol. If it is higher, gasoline will be the smarter choice for your wallet.
Factors that go beyond the price at the pump
The choice of fuel should not be limited solely to the cost per kilometer driven. Gasoline, as it has a greater energy density, generally offers greater autonomy. Isso means that, with one tank of gas, you will travel a greater distance before needing to stop to refuel, an important factor for those who frequently undertake long trips.
On the other hand, ethanol can provide a gain in power and torque in many flex engines. As it has a higher octane rating, biofuel allows the engine to work with a more advanced ignition point, resulting in faster responses to the accelerator and a feeling of greater sportiness when driving, which can be a differentiator for some drivers.
The environmental aspect is also a relevant point in the decision. Sendo a fuel from a renewable source, derived from sugar cane, the life cycle of ethanol emits significantly fewer greenhouse gases compared to gasoline, which is a petroleum derivative. Para drivers with greater ecological awareness, opting for ethanol is a way to reduce the carbon footprint of your journey.
Geographic location directly affects the viability of each fuel. In sugarcane producing states, such as São Paulo, the tendency is for ethanol to have a more competitive price. Já in regions further away from production centers, logistics costs can make gasoline a more economically attractive option during most of the year.
Advantages and disadvantages of each option
Ethanol stands out for its lower environmental impact and its potential to increase engine performance. Além Furthermore, during sugarcane harvest periods and in producing regions, its price can be quite attractive. However, its main disadvantage is its shorter range, requiring more frequent visits to the gas station.
Gasoline, in turn, has greater autonomy as its main asset, providing more convenience on trips and in daily use. In places with harsh winters, cold starting tends to be easier with gasoline, although modern ethanol preheating systems have minimized this problem. Seu downside is that it is a fossil fuel, with a greater environmental impact and prices that are often linked to international oil prices.
Practical tips to maximize savings
Regardless of the choice between ethanol and gasoline, adopting efficient driving and maintenance habits is essential to save money. Manter tires are always inflated to the correct pressure, carrying out vehicle inspections on time, such as changing oil and filters, and avoiding sudden acceleration and braking are practices that optimize the consumption of any fuel. Além In addition, using price comparison apps can help you find the cheapest gas stations in your region, guaranteeing additional savings with each fill-up.
