When it comes to fuel efficiency and mileage, diesel engines are known to outperform their gasoline counterparts. But just how much better is the fuel economy of diesel vehicles? What kind of real-world mileage can you expect from a modern diesel car or truck? In this comprehensive guide, we’ll take a close look at the average diesel mileage you can expect and the factors that influence it.
The Benefits of Diesel
There are a few key reasons why diesel engines achieve better mileage compared to gasoline engines:
- Diesel fuel contains about 10-15% more energy per gallon than gasoline. This means a gallon of diesel fuel can take you further.
- Diesel engines have higher compression ratios, allowing more efficient combustion of the fuel.
- Diesels provide torque at lower RPMs, so they don’t need to work as hard to accelerate and maintain speed.
Modern diesel vehicles also benefit from advanced fuel injection and turbocharging systems that further optimize combustion efficiency. Overall, the fundamental differences between diesel and gasoline give diesel-powered vehicles an edge when it comes to squeezing more miles out of every gallon.
Average Diesel Mileage by Vehicle Type
Now let’s look at some real-world numbers. Here are the latest diesel mileage averages reported by the EPA for different vehicle classes:
|Average Diesel Mileage
As you can see, there is quite a range depending on vehicle size and class. Small diesel cars can achieve 40 mpg or more on the highway, while full-size diesel trucks average closer to 20 mpg. However, even the lowest averages are notably better than comparable gasoline models.
What Impacts Diesel Mileage?
While diesel engines offer an inherent efficiency advantage, there are many variables that can impact your real-world mileage:
- Vehicle size and weight – Heavier vehicles require more effort to accelerate and move, lowering mileage.
- Engine size – Vehicles with larger, more powerful engines consume more fuel under acceleration.
- Fuel type – Lower sulfur diesel tends to have slightly better fuel economy than higher sulfur blends.
- Driving style – Aggressive acceleration and high speeds lower MPGs. Gentle acceleration improves it.
- Speed – Mileage decreases significantly above 50 mph as wind resistance increases.
- Operating conditions – Stop-and-go, city driving lowers mileage compared to steady highway driving.
- Maintenance – Poor maintenance and issues like low tire pressure can reduce fuel economy.
- Terrain – Hilly and mountainous routes lower mileage compared to flat terrain.
- Cargo/passengers – Added weight in the vehicle reduces fuel efficiency.
- Air conditioning – Running A/C uses extra engine power, lowering MPGs.
- Accessories – Add-ons like roof racks increase aerodynamic drag.
- Cold weather – Colder temperatures can reduce mileage by up to 20%.
Maximizing your diesel vehicle’s mpg requires paying attention to these factors and driving in a fuel-efficient manner as much as possible.
Tips to Improve Diesel Mileage
Here are some expert tips to squeeze every last drop of fuel economy out of your diesel engine:
- Accelerate slowly and gently.
- Maintain low constant speeds when possible.
- Use cruise control on highways.
- Limit excess cargo weight.
- Make sure tires are properly inflated.
- Change air filters frequently.
- Use recommended engine oils.
- Follow the maintenance schedule.
- Limit unnecessary idling.
- Reduce the use of A/C when possible.
- Avoid running electrical accessories.
- Don’t top off the fuel tank.
- Remove unnecessary cargo racks or tonneau covers.
- Plan routes to minimize stops and maximize highways.
- Avoid carpooling with diesel vehicles.
Drivers who pay close attention to these fuel-saving techniques can maximize their mileage and may even exceed EPA estimates in real-world driving.
Mileage Variance Between Models
While the averages we’ve looked at give a general idea of diesel fuel economy, there can be notable differences between various models. Here’s a sample of mileage variances within some popular vehicle classes:
Midsize Diesel Cars
- Toyota Camry Diesel – 32 mpg combined
- Honda Accord Diesel – 36 mpg combined
- Chevy Malibu Diesel – 39 mpg combined
Full-Size Diesel Trucks
- Ram 1500 EcoDiesel – 24 mpg combined
- Ford F-150 Powerstroke – 25 mpg combined
- Chevy Silverado Duramax – 33 mpg highway
There are always trade-offs between power, capacity, and fuel efficiency. But in general, newer diesel models tend to have an edge when it comes to optimizing mileage without sacrificing performance.
Diesel Costs vs. Gasoline
For most buyers, fuel efficiency is only half of the equation when weighing gasoline vs diesel. You also have to consider fuel costs. Here’s a look at some of the key factors:
- On average, diesel costs 20-40 cents more per gallon than regular gasoline.
- However, diesel vehicles go further on a gallon, making the cost per mile driven comparable to gasoline.
- Maintenance costs are generally higher on a diesel due to more expensive oil changes, fuel filters, etc.
- Diesel engines have a reputation for greater longevity and engine life.
- Diesel vehicles may have higher resale value, offsetting higher acquisition costs.
The benefits of greater fuel efficiency often offset the higher prices at the pump. And choosing a fuel-efficient model helps maximize the financial case for switching to diesel.
Gasoline vs. Diesel: An Example
Let’s compare two midsize truck models – one diesel, one gasoline – to demonstrate the mileage and cost differences:
|Fuel Cost per Gallon
|20 combined mpg
|Chevy Colorado Duramax
|25 combined mpg
For 15,000 miles of annual driving, the gasoline Tacoma would consume 750 gallons and cost $2,625 to fuel. The diesel Colorado would use 600 gallons and cost $2,400. In this example, the diesel has a $225 fuel cost advantage per year while providing enhanced driving performance.
The Verdict on Diesel Mileage
Modern diesel engines provide significant fuel efficiency benefits over comparable gas models – typically 20-35% better mpg. Real world averages range from 40 mpg in small diesel cars to around 20 mpg in full-size diesel trucks.
Better fuel economy is inherent to diesel design, but many variables impact the mileage you’ll experience. Choosing an efficient model and practicing fuel-saving driving techniques is key to maximizing diesel mpg.
The higher cost of diesel fuel is usually offset by achieving more miles per gallon. And with today’s advanced emission-control systems, diesel vehicles provide a strong combination of power, range, drivability, and efficiency.
For drivers covering lots of miles, especially at highway speeds, a modern diesel can be a great way to save money at the pump through superior fuel economy.