Five popular car mods that lead to decreased fuel economy

Modifying cars is a fun way to personalize them and enhance performance to match a driver’s style and preferences. The automotive aftermarket is packed with products you can add to make your car truly your own. These modifications can be cosmetic or performance-oriented, but like any change, they come with trade-offs, usually, fuel consumption.

With gas prices climbing at an alarming rate this month, it’s a good time to review some popular car mods and consider how they might negatively affect your fuel economy.

If you’re looking to save money during the oil crisis, here are five modifications you should avoid.

Rear wings and spoilers make the silhouette of cars, particularly sedans, appear more sporty, but they will cause your car to use more fuel. See, the purpose of rear wings is to produce more downforce to give cars extra grip on the road. That’s why race cars, like Formula 1 cars, have massive rear wings to keep them stable at high speeds.

Spoilers serve a slightly different purpose. While they can add downforce, they’re often designed to manage airflow and reduce drag. Factory-installed spoilers are engineered to optimize a car’s aerodynamics, whereas aftermarket ones may not be as effective, it could even hurt efficiency. Unless you have expertise in aerodynamics and access to tools like a wind tunnel, it’s usually best to leave your car’s exterior as it is.

Some car modifications not only hurt fuel economy but can also be considered more cosmetic than practical, and sometimes even tacky. Take fake hood vents, for example. These are usually plastic accessories that stick onto your car with adhesive, so no cutting or drilling is required. While they may give the illusion of a performance upgrade, they disrupt the car’s carefully designed airflow, reducing aerodynamic efficiency and potentially increasing fuel consumption.

Wide-body kits are another popular but problematic modification. By widening the car’s fenders and body panels, they can make a vehicle look aggressive and sporty. However, the extra weight and altered airflow can significantly reduce efficiency. The car’s engine has to work harder to overcome the added drag, which increases fuel consumption, especially at highway speeds. Unless the kit is professionally engineered with aerodynamics in mind, these modifications are more for show than performance.

Aftermarket wheels and tires are one of the most common upgrades people make to their cars. A bigger set of wheels paired with wider, low-profile tires can dramatically improve a car’s stance and give it a more aggressive look. However, these upgrades can also hurt your fuel economy.

Larger wheels and wider tires increase rolling resistance, which means the engine has to work harder to keep the car moving. Heavier wheels also add what’s known as unsprung and rotational weight, making it harder for the car to accelerate and maintain speed efficiently. This extra effort translates to higher fuel consumption, especially in stop-and-go driving.

There is also the matter of tire width. Wider tires provide more grip because they place more rubber on the road, but that larger contact patch increases friction. While this can improve handling, it also means the engine must burn more fuel to overcome the added resistance. Unless you’re using your car to take to the track or off-road, the stock wheels and a good set of highway terrain tires are always optimal.

Engine tuning and ECU remapping are popular upgrades for drivers looking to squeeze more performance out of their cars. Modern vehicles rely on an engine control unit, or ECU, to manage fuel delivery, ignition timing, and boost pressure in turbocharged engines. By reprogramming the ECU, tuners can increase power and torque by adjusting these parameters.

However, the added performance often comes at the expense of fuel economy. Performance-focused tunes typically increase fuel delivery or boost pressure to generate more power, which means the engine burns more fuel. While factory ECU settings are carefully balanced for efficiency, emissions, and reliability, aftermarket remaps often prioritize performance, which will lead to higher fuel consumption. Oh, and those 'pops and bangs' tune that enthusiasts love? Those are made by making the engine run rich and letting unburnt fuel reach the exhaust, which means extra consumption.

Another popular mod is aftermarket exhausts. These are a go-to for drivers who want their cars to sound louder and sportier. Swapping out the factory exhaust for a freer-flowing system can reduce back pressure and help the engine breathe a bit better. In some cases, this can unlock small performance gains, especially on turbocharged engines.

However, the downside is that these systems can also encourage higher fuel consumption. A louder, more responsive exhaust often tempts drivers to push the throttle more, which naturally burns more fuel. Some setups may also reduce the efficiency of the factory exhaust design, which is usually tuned to balance performance, emissions, and fuel economy.