Why Your Car’s Fuel Economy Keeps Getting Worse

There’s hardly anything worse than the realization that fuel expenses keep getting worse and worse each month. The same car, the same commute – but the fuel isn’t lasting like it used to. Many motorists just assume it’s the price of fuel or their imagination, but worsening fuel economy is a factor – and usually, it means that something is wrong.

Dirt or Bad Spark Plugs Reduce Efficiency

Spark plugs are one of those things that slowly go bad that people don’t even realize just how bad they are getting. They fire thousands of times per minute. Over tens of thousands of kilometers, they wear down and the gap between electrodes widens. This means that the spark is weaker and less reliable.

Weaker sparks mean incomplete combustion. This means that fuel isn’t burned as effectively, wasting energy resources and power. Thus, fuel economy is worse from the start as the engine needs to muster power but finds itself lacking. In time, as the spark plugs go bad, this four percent inefficiency might grow to ten percent, then fifteen percent.

Manufacturers boast recommended replacement intervals of 50,000 to 100,000 kilometers depending on the spark plug type but most drivers exceed those numbers drastically. While the car still works – maybe a little rougher, maybe a little less powerful – fuel economy steadily lowers without being noticed. Thus, over a year, the waste in extra fuel tends to far surpass the cost of new plugs instead of a simple routine check.

Air Filter Restrictions Starve the Vehicle

However, cars do require huge amounts of air. If air filters are clogged up, this puts unnecessary pressure on engines to pull as much air as they can from what’s made available. Consider an air filter like breathing through a cloth. Sure, you can do it – but it’s effort and you’ll never perform at 100%.

An air filter just sits there absorbing dirt, dust, pollen, debris every time you turn the engine on. In good conditions, air filters should last thirty-thousand kilometers plus. Drive on dirt roads frequently and even fifteen-thousand kilometers might be stretching it before it needs replacement. Clogs are subtle, however. There’s no red light that pops up saying that the air filter is dirty and all engine performance declines at once. Instead, performance gets worse and worse over time.

Thus when you take the vehicle for a routine car service, these smaller items like filters get checked and replaced before problems occur as opposed to waiting until critical failure exists.

Tires Support More than You Think

The lower tire pressure also increases rolling resistance meaning that if tires are underinflated by five to ten PSI, this might drop fuel economy by 2% to 3%. If tires are underinflated by 15 to 20 PSI or more, that’s a 5% drop in fuel economy.

Tires inevitably lose tire pressure from temperature changes, nails, slow leaks from abnormal valve stems – these happen gradually and most drivers don’t check their tire pressure frequently enough to make sure that tires have adequate inflation for the best drive possible.

Yet low tires don’t feel any different than regular tires for the most part. They’re a little floppier on the road; they might handle with slightly less responsiveness – but most people don’t connect that small difference to tire pressure. Even worse, people burn out unevenly and go through tires faster due to these poor habits.

Oxygen Sensors Fail With Time

Then, there are oxygen sensors which are designed to estimate exhaust output levels for better mixtures to optimize performance and efficiency. However, over time – as sensors wear out – their readings become skewed.

A faulty sensor indicates that the engine is running rich – too much fuel relative to air – and this obviously ruins fuel efficiency because you’re wasting resources. However, if your car is running normally – as many people drive without notice – fuel efficiency declines combined with a slight smell of fuel from the exhaust.

Most oxygen sensors last anywhere from 80,000 km to 160,000 km but they can fail sooner if poor quality goes in or maintains engines aren’t kept at par. However, lights do not come on until failure is absolute; hence performance slowly declines without anyone batting an eye.

Fuel Systems are Clogged From Deposits

Fuel injectors spray fine lines of output into combustion chambers for effective generation; however, build up over time between additives and combustion limits nozzle output.

In addition, many engines have intake valves which collect carbon deposits from inside; especially direct gasoline ones where valves atomize fuel in with air particles for combustion. The driveability outside of this congestion is so slight that people barely notice an impact but overtime they grow unstintingly worse.

Fuel system cleaning can help restore lost potential; however, it’s often one service get neglected because cars seem fine without it. Meanwhile deposits cause problems well before observable parameters have grown.

Extra Weight Costs Fuel

This is more about driver habits than their mechanics but it is relevant. It costs extra weight in the trunk or back seat – 1% extra per 50 kg in a regular sized car. That bike rack you leave on the top year-round? It can cost 10-25% fewer highway miles depending on its aerodynamic edge (or lack thereof).

People acquire things in their cars; sports equipment, tools, emergency supplies – none individually amount to too much weight – but when placed together they add up quickly. That bike rack looked good for that one camping trip; leaving it on year-round costs.

Driving Style Increases Unnoticed Over Time

Finally, fuel economy comes down to driving style – and since people spend a significant amount of their time in their cars today this can change gradually without people noticing.

People start accelerating rapidly versus slowly or driving constantly at 100 instead of 90 km/h (60 instead of 55 mph). People start braking harder or more frequently without even realizing they’re doing so; especially in city traffic where corners crop up.

This can kill city economy by up to 15-30% if drivers are never paying attention to easing off gas or anticipating stops through careful coasting instead of heavy braked approaches.

The good news is almost everything that causes fuel economy to worsen can be fixed over time. Get your vehicle serviced regularly and worn plugs will be replaced before efficiency drops; clogged filters won’t back up and reduce breathing capacity.

Checking tire pressure takes five minutes every month – not doing so wastes 2-5% immediately – and diagnosing mechanical issues comes from proper service diagnostics and encouragement for effective repair work rather than simply getting used to problems over time.

Multiple efficiency draining problems compound over time therefore taking care of them all at once can produce impressive results – almost immediately after each component is brought back to normal if not new efficiency specs.

Over time most parts progressively deteriorate – they don’t get better – they cause problems when left alone for too long where each day becomes one red flag after another for proper adjustment or serviced repair work.

Fuel economy doesn’t need to worsen over time; if it does – serve your vehicle before bigger issues arise down the line that will cost even more money!