Fuel Economy Comparison: Hybrid vs Diesel vs Gas

March 9, 2012

Cars have different fuel saving technologies with unique pros and cons, as shown in this fuel economy comparison of hybrid, diesel, and gas solutions.

Many people are interested in the fuel economy comparison between the three main fuel types of cars that are being offered: gas, diesel and hybrids. Each has their own advantages and disadvantages. This article will provide an overview of how fuel economy relates to each, as well as tips (ranging from regular automobile maintenance to the way you drive it) to increase fuel efficiency.

The Pros and Cons of Hybrid, Diesel and Gas

All three have their pros and cons.

Gasoline Pro

  • Gas engines produce high horsepower

Gasoline Con

  • The fuel is more expensive

Diesel Pros

  • Diesel is cheaper than gasoline
  • Offers more torque than gas engines
  • The engine and vehicle as a whole lasts longer
  • Clean diesel technologies, like ultra low sulfur diesel, are being looked into and implemented

Diesel Cons

  • Produces less horsepower than gas engines
  • Engines are loud and emit pollutants

Hybrid Pros

  • Offers the best fuel efficiency
  • Lightweight, run smoothly and quietly
  • Can also use electric power, which makes for low emissions vehicles

Hybrid Con

  • Pricier than regular gas counterparts

Gas vs Hybrid

Many people have the debate of buying a gas car or a hybrid of the same type. Some cars that have both a hybrid and gas counterpart are the Ford Escape, the Honda Civic and the Lexus RX. The hybrid clearly gets more fuel economy than the gasoline engine--most of the time the difference is at least 25%, but often more than 33%. On the outside, it seems like the gas savings will be great. However, it may take several years to catch up to the savings on gas due to the higher base cost of a hybrid. A hybrid usually is several thousand more than the regular model, and sometimes it is much more extreme. The Escape hybrid costs $8,000 more than the base gas model, and the Lexus RX hybrid costs over $10,000 more as a hybrid. The gas savings really is not there when you look at it from an energy cost standpoint. Fuel economy-wise though, hybrids blow gasoline cars out of the water.

Diesel vs Hybrid

Diesel engines typically increase gas mileage by 30 to 35% over gasoline engines--about the same as hybrids. So when it comes to fuel economy, they are actually fairly even. The break is then in the hybrids side because those cars are often ULEV, or Ultra Low Emissions Vehicles. Some diesel cars can't even be driven in certain states because they don't meet the emissions standards of those states. If you take the best hybrid vs the best diesel car, the hybrid will actually win. The Prius would be the tops in the class right now and that gets 51 miles per gallon. The best diesel car may be the Jetta TDI and that gets about 20% less at 42 miles per gallon. When you compare gas mileage between the three top types of cars, it is clear who wins. Hybrids offer the best mileage out of the three. Diesel comes in close, but other factors cause it to lose to a hybrid. Gas is in last place, and is typically the cheapest of the three.

Tax Incentives for Buying High Fuel Economy Cars

The price of a barrel of oil has skyrocketed over the years, and in response automakers have stepped up their efforts to met consumer demand for higher fuel economy in passenger cars and light trucks. The US Government has also stepped up their efforts to promote the innovation of cleaner, more energy-efficient vehicles by creating tax incentives to auto manufacturers and consumers who purchase new fuel-efficient vehicles. There are tax credits available under the Energy Policy Act of 2005 (extended in 2009 by the American Recovery & Reinvestment Act and amended Emergency Economic Stabilization Act of 2008) that can save anywhere from $1,300 to $7,500 on a federal tax return. For consumers, the most common car tax incentives are the alternative fuel and hybrid tax credit and the plug-in electric vehicle (EV) tax credit. An easy to follow summary of the available tax credits can be found at the U.S. Department of Energy's website.

How Kinetic Energy Can Increase Fuel Efficiency

Automotive engineers have been working to increase fuel efficiency in automobiles for years. Developments in aerodynamics, engine technology, and light-weight materials have improved gas mileage significantly. The process of capturing kinetic energy has also proven to be a successful way in powering cars efficiently. Below you will find what kinetic energy is and how it boosts fuel economy.

Kinetic Energy
Any object that moves has kinetic energy. In other words, it is the energy of motion. There are different types of kinetic energy a moving car produces. For example, kinetic energy is rotational when the car wheels are revolving. Most hybrids capture this energy with a technology called regenerative braking.

Regenerative Braking
Most automobiles do not have regenerative braking. Non-hybrid cars are mechanically slowed and stopped by brake pads that clamp down. The rotational kinetic energy in the spinning wheels is absorbed by the brake pads and the potential energy goes unused in powering the vehicle. Hybrid cars use a combination of an electric motor and mechanical braking to slow down and stop. The electric motor slows down the car initially when the brake pedal is applied. The motor collects the kinetic energy produced by the rotating wheels and stores it in the car's batteries. Then the brake pads are put to use to complete the halting motion. Brake pads are usually applied immediately when an emergency situation occurs. After the electric motor captures the kinetic energy, the motor can utilize the batteries to power the car alone or in combination with a gasoline-powered engine.

Technologies like regenerative braking are some of the most important features on eco-friendly cars today. In the future, engineers will invent ways to capture other sources of energy that vehicles produce.

Why Fuel Economy Mileage Varies between Drivers

When it comes to fuel economy mileage, it truly varies depending on the driver. First, there is a big difference between the stated highway mileage and city mileage that a car gets and the real world MPG of that same car. When the car is officially tested it is being tested is being tested under the specific testing conditions and not just in everyday driving. When the human element is brought into play, it changes many things and one of those things is the gas mileage. Everybody is different, and because of this, everyone drives differently than one another. Because of this, the gas mileage for the same car can vary between different drivers.

The driving conditions do affect the mileage of the car as well. If you are comparing someone who only drives in a big city like New York City, they surely will have lower mileage totals than someone who drives in an open road in Kansas. In addition to that, the way you drive also will affect the numbers. You may go the same amount of miles, but one person may use up a lot more gas due to more accelerations. They may get to their place of destination quicker, but they will use up more gas. If someone coasts there way at a constant speed, they are limiting their acceleration, and will use much less gas than someone who does the opposite. As you can see, there will be a big difference from the stated numbers by the EPA, and then another difference between the drivers of the same exact vehicle.

Why Fuel Economy Ratings Differ from Actual MPG

When it comes to official fuel economy ratings, the ratings on your car are those achieved under the specific conditions of the EPA fuel economy test. Often times the real world mpg that you achieve will be different. There are many reasons for this. First, the car they are testing is brand new and has no problems. As your car gets older, there are likely to be maintenance issues with your car that you may be unaware of. Many car parts can affect your gas mileage. Some of them are the air filters, fuel injectors, spark plugs, oxygen sensors, etc. All of these contribute to lowering your real mpg if there is something wrong with them. Another reason why you get different miles per gallon numbers is the way you drive. The cars were driven under very specific conditions during the EPA fuel economy tests.

When you are the driver, there are many differences. Many people are aggressive drivers meaning that they accelerate a lot, and sometimes for no good reason at all. You should always try to maintain a constant speed, but often times this doesn't happen. Another reason is that people do like to speed while driving. 55 miles per hour is an efficient speed for gas usage, but many people go faster causing their MPG ratings to drop. Lastly, in the real world there is traffic. Traffic causes many stopping and starting situations, which causes drivers to accelerate just to get up to 10 or 15 miles per hour. This wastes a lot of gas. Overall, there are many reasons that the fuel economy ratings in your manual differ from what you are actually getting.

How to Improve Fuel Efficiency with Maintenance Checks

Fuel efficiency can be kept up just by keeping your vehicle on a regular maintenance schedule, like changing your air and fuel filter, your spark plugs, checking the air pressure in your tires or doing an oil change. These are things that you should be doing already as a car owner. These four tips will help you to make sure your car runs at its best with optimum fuel efficiency.

Make Sure Your Tire Inflation Is Correct
Having tires that are under-inflated causes your car to work harder to maintain speed. This causes your engine to maintain higher than normal RPMs in order to counteract the resistance of the under-inflated tire. Always remember to check the owner's manual for the proper tire pressure and not the sidewall of the tire. Pressures printed on the sidewall are generally considered to be the maximum safe pressure a tire can handle, not what your car requires, and having overinflated tires can be just as bad. Never check your tire pressures after a drive, as the heat from the road makes the pressure go up. The best time to check your tire pressure is in the morning, when your car has been sitting overnight.

Change Your Spark Plugs When Needed
Having old or bad spark plugs can cause fuel to not burn completely inside your cylinder. This leaves carbon deposits on your cylinder walls after combustion, which can ignite new fuel too soon, causing pre-ignition and pinging. Be sure to get the spark plugs your vehicle manufacturer recommends - more expensive isn't necessarily better. In fact, in the case of spark plugs, not only could you be throwing your money away, you could be damaging your engine. In most cars, you can do this yourself in an afternoon and save money on repairs.

Check Your Wheel Alignment
While it might not seem like something that's related to fuel efficiency, having misaligned wheels increases the friction between your tires and the road. Doing this forces the engine to work harder to attain the same speed as a perfectly aligned vehicle. You should also never skip out and do just your front wheels. Rear wheels can become misaligned too, even though they don't do the turning on most vehicles.

Change Your Oxygen Sensors
Oxygen sensors (commonly called O2 sensors, or just O2s) help monitor and maintain the air to fuel ratio in your engine. An O2 sensor's life can vary significantly - anywhere from 15,000 miles to 50,000 or more, so if you notice a sharp decrease in your fuel economy, they can be a good fix. Faulty oxygen sensors are known to decrease your fuel efficiency up to a whopping 40%, but even old and worn (but still perfectly functioning) sensors can impact your gas mileage by almost 20%. Changing your O2 sensors won't increase your efficiency immediately, however. It may take two to three fill ups for your vehicle's computer to adjust to the new air to fuel ratio.

Fuel efficiency isn't something limited just to hybrid cars and small vehicles. Anyone can benefit from these four simple tips, whether they drive a Toyota Prius or a Chevrolet Suburban. You'll notice the savings and thank yourself every time you stop at the pump.

How to Read the New EPA Fuel Economy Stickers

The U.S. Environmental Protection Agency has changed the criteria it uses to estimate the EPA fuel economy. When car buyers go car shopping, they find a label affixed on the car window that provides valuable information about vehicle MPG (miles per gallon). These figures reflect the number of miles a car can travel per gallon of gas. With an increase in fuel cost and vehicle emissions, the EPA has now reworked fuel economy estimates, to closely match real word driving results. The new fuel economy stickers determine the expected range any given vehicle can travel within cities and highways, and this helps budget fuel cost. The following points should be kept in mind when reading the new EPA fuel economy stickers.

  • According to the new stickers, most vehicles will carry a lower MPG number. These new estimates take into consideration, driving at faster speeds, increased acceleration, use of air conditioners, and driving in colder temperatures. The new stickers are also designed for easier reading
  • The fuel economy labels reflect MPG estimates for city drivers and highway drivers. The number listed on the top left hand corner of the sticker displays the City MPG and the range of fuel economy for city drivers. The number listed on the top right hand corner of the sticker displays the Highway MPG and the expected range of fuel economy for most highway drivers
  • Between these two estimates, the sticker will also display the estimated annual fuel cost. This cost is based on fuel cost of $2.80 per gallon and 15,000 miles driven annually. However, this figure is just an estimate and the actual annual fuel cost will vary according to the number of miles driven, and varying fuel prices.
  • If you read the bottom half of the window sticker, you will also find out the combined fuel economy of the vehicle. This information helps you to compare the combined city-highway MPG of any vehicle, to others in the same class
  • Although these estimates are close enough to determine actual fuel cost and vehicle mileage, they serve as mere guidelines. The actual mileage of any vehicle depends on how it's driven and serviced

New Stickers
The fuel economy estimates for 2007 and older vehicles weren't designed after taking into consideration aggressive acceleration, high usage of air conditioners and driving in extreme weather conditions such as wind and snow. Due to this, the new stickers display MPG values that are much lower than before. Starting from model year 2008, most vehicles will have new stickers with the revised fuel economy estimates.

Fuel economy is soon becoming an important factor for new car buyers, as energy efficient vehicles not only save money due to reduced fuel costs, but also reduce climate change with lower carbon emissions. The fueleconomy.gov website has a section where drivers can compare old and new MPG estimates or print out a fuel economy guide. In addition, the website provides detailed information on gasoline prices, tax incentives for new hybrid purchases and tips to reduce gas usage.

The 7 Most Important Gas Saving Tips

There are many gas saving tips that you should use to improve fuel efficiency. Many people may give you tips to save gas, but there are a lot of wrong tips out there. Use this article as a checklist of things to do to help increase your MPG.

  1. The first thing you can do is go down to your mechanic and have him look over your car. There are many potential maintenance issues that can help decrease your gas mileage if they are not working properly. The fuel injection system is important to make sure the engine is getting enough fuel. However, there are sometimes leaks in this system that causes more or less gas to get to the engine, lowering your gas mileage. Your car has air filters which can get clogged. They may be the biggest culprit of gas mileage, as they decrease your fuel economy by as much as 20%. One other problem sometimes is with the spark plugs
  2. While you are at the mechanic, have him fill your tires with air to the right pressure. This can improve fuel efficiency by up to 5%
  3. Over 150 million gallons of gas evaporate from tanks of cars in the United States every year. The cause of this is not screwing your gas cap back tightly. Just by doing this, you can save some gas. Remember, it all adds up
  4. If you like to drive with the air conditioner on, then you are wasting gas, because the air conditioning unit uses a ton of power to run. To combat it, just turn it off and open the windows for a nice breeze. Obviously if it is 90 degrees out, then turn the air on
  5. Making your car lighter is another way to increase your gas mileage. This is a reason why trucks and SUVs get lower mileage, and that is their weight. If you have unnecessary items on or in your car like a roof rack, or unwanted things in your trunk, remove them to lighten the load
  6. A big part of wasting gas is how you, the driver, operates the car. The faster you accelerate, the more you rev your engine, and that means more gas is being used. Often times you accelerate for no reason other than it feels like you are going slow. When you see a red light, take your foot off the gas, or if you see traffic up ahead, coast. There is no reason or benefit to catching up to the traffic. It actually detracts from your gas mileage because you have to keep starting and stopping. Avoid traffic when you can
  7. Stay at a constant speed of 55 miles per hour. Anything higher and you are using more gas than you need to. A good car tool is cruise control because it can keep the car at any speed you want. Constant speeds mean no acceleration, so you get to save some gas