2005 GMC Sierra 2500 HD 2WD CNG: MPG and fuel economy
The 2005 GMC Sierra 2500 HD 2WD CNG is rated by the U.S. Environmental Protection Agency at 9 combined MPG, with 8 MPG in the city and 11 MPG on the highway. That lands well below the average for cars in the Standard Pickup Trucks 2WD class in the same model year.
This page collects every fuel-economy figure the EPA publishes for the 2005 GMC Sierra 2500 HD 2WD CNG. Below you will find the headline combined, city, and highway MPG, the estimated annual fuel cost at three different driving levels, the tailpipe CO₂ emissions, and a full breakdown of the engine and drivetrain.
Key takeaways
- Returns 44% worse combined MPG than the average car in the Standard Pickup Trucks 2WD class for the 2005 model year (16.2 MPG class average).
- The most efficient car in the Standard Pickup Trucks 2WD class for the 2005 model year is the Ford Ranger Pickup 2WD at 21 MPG.
- EPA estimates this car costs around $14,000 more in fuel over five years than an average new vehicle of the same model year.
Fuel economy at a glance
These are the EPA's official ratings for the 2005 GMC Sierra 2500 HD 2WD CNG. The numbers come from a standardised laboratory test cycle and are the same figures that appear on the window sticker of every new car. Real-world mileage varies with driving style, weather, fuel quality, and how heavily loaded the car is.
Combined MPG is a 55/45 weighted blend of the city and highway test cycles. The EPA uses it as the single number you can compare across the entire dataset, including hybrids and EVs (which use the equivalent MPGe figure).
| Combined MPG | 9 MPG |
| City MPG | 8 MPG |
| Highway MPG | 11 MPG |
| Annual fuel cost | $4,950 |
| Tailpipe CO₂ | 781 g/mi |
| Fuel type | CNG |
How the 2005 GMC Sierra 2500 HD 2WD CNG compares
The 2005 GMC Sierra 2500 HD 2WD CNG returns 9 combined MPG. Cars in the Standard Pickup Trucks 2WD class for the same model year average 16.2 MPG, which puts this car behind the class average by about 44%.
The most efficient car in the Standard Pickup Trucks 2WD class for the 2005 model year is the Ford Ranger Pickup 2WD at 21 MPG. The bar chart below puts the GMC Sierra 2500 HD 2WD CNG alongside the class best and the class average so you can see the full picture.
For broader context, the average new car of the 2005 model year (across all classes) returns 18.5 MPG. Larger vehicles pull the all-cars average down, so do not use that figure on its own to judge a small car or a hybrid. The full list of the most efficient cars of the 2005 model year is on its own page.
Annual fuel cost across driving patterns
The headline annual fuel cost the EPA publishes assumes 15,000 miles of driving per year and a fuel mix of 55% city and 45% highway. The dollar figure is calculated using the EPA's current reference price for compressed natural gas, which is $2.96/gallon. EPA updates that reference periodically rather than tracking live pump prices, so treat it as a window-sticker estimate rather than today's pump number.
The table below scales the EPA's number to three common driving patterns. The combined MPG and the reference fuel price stay constant, only the annual mileage changes. To get a current-prices estimate, take your local gas price and multiply by 1666.7 gallons (the car's annual consumption at the rated MPG).
| Driving pattern | Estimated annual fuel cost |
|---|---|
| Light driver, 7,500 miles per year | $2,475 |
| Average driver, 15,000 miles per year | $4,950 |
| Heavy driver, 25,000 miles per year | $8,250 |
Compare against other Standard Pickup Trucks 2WD for 2005
If you are cross-shopping the 2005 GMC Sierra 2500 HD 2WD CNG, the most useful comparison is against the other cars in the Standard Pickup Trucks 2WD class for the same model year. The list below shows the highest-MPG peers, ranked from most to least efficient. Click any of them to open its full page.
The Ford Ranger Pickup 2WD leads this group at 23 MPG, 14 MPG ahead of the 2005 GMC Sierra 2500 HD 2WD CNG.
Specifications
The 2005 GMC Sierra 2500 HD 2WD CNG runs a 6-liter 8-cylinder engine paired with a automatic 4-spd, sending power through rear-wheel drive.
Engine, transmission, and drivetrain together drive most of the variation in fuel economy across trims. A larger engine moves the car with less effort but burns more fuel. A turbo lets a small engine punch above its weight, often without much MPG penalty. All-wheel drive adds traction and weight, and usually costs a couple of MPG compared with two-wheel drive of the same engine.
- Vehicle class
- Standard Pickup Trucks 2WD
- Engine
- 6L 8-cylinder
- Transmission
- Automatic 4-spd
- Drivetrain
- Rear-Wheel Drive
- Fuel type
- CNG
- Annual petroleum use
- 0.2 barrels per year
Common questions about the 2005 GMC Sierra 2500 HD 2WD CNG
Quick answers to the questions people most often search for when looking up the 2005 GMC Sierra 2500 HD 2WD CNG.
-
Is the 2005 GMC Sierra 2500 HD 2WD CNG fuel efficient?
Not particularly. The 2005 GMC Sierra 2500 HD 2WD CNG returns 9 combined MPG, which trails the average car in the Standard Pickup Trucks 2WD class for the same model year by about 44%. -
What MPG does the 2005 GMC Sierra 2500 HD 2WD CNG get?
The EPA rates the 2005 GMC Sierra 2500 HD 2WD CNG at 9 combined MPG, 8 MPG in city driving, and 11 MPG on the highway. Real-world numbers depend on your driving style, the weather, and how loaded the car is. -
How much does it cost to fuel a 2005 GMC Sierra 2500 HD 2WD CNG per year?
The EPA estimates an annual fuel cost of $4,950 for the 2005 GMC Sierra 2500 HD 2WD CNG. That figure assumes 15,000 miles of driving per year, a 55% city and 45% highway split, and the EPA's published average fuel price for the rated fuel grade. -
What fuel does the 2005 GMC Sierra 2500 HD 2WD CNG use?
The EPA lists the 2005 GMC Sierra 2500 HD 2WD CNG as running on natural gas. Using a different grade than the manufacturer specifies can affect fuel economy and engine longevity. -
How much CO₂ does the 2005 GMC Sierra 2500 HD 2WD CNG emit?
Tailpipe CO₂ emissions are 781 g/mi. Multiplied across a typical year of driving (15,000 miles) that works out to about 11,717 kilograms of CO₂. -
What is the difference between the city and highway MPG of the 2005 GMC Sierra 2500 HD 2WD CNG?
City driving returns 8 MPG and highway driving returns 11 MPG, a gap of 3 MPG. The two figures are close enough that the car will hold its rated efficiency well across most driving patterns. -
What engine is in the 2005 GMC Sierra 2500 HD 2WD CNG?
The 2005 GMC Sierra 2500 HD 2WD CNG has a 6-liter 8-cylinder engine. -
What transmission and drivetrain does the 2005 GMC Sierra 2500 HD 2WD CNG have?
The 2005 GMC Sierra 2500 HD 2WD CNG comes with a automatic 4-spd transmission and rear-wheel drive. -
How does the 2005 GMC Sierra 2500 HD 2WD CNG compare to the best car in its class?
The most efficient car in the Standard Pickup Trucks 2WD class for the 2005 model year is the Ford Ranger Pickup 2WD at 21 combined MPG. The GMC Sierra 2500 HD 2WD CNG returns 9 MPG, a gap of 12 MPG. If you are comparing on fuel economy alone, the class leader is worth a look. -
How much more does the 2005 GMC Sierra 2500 HD 2WD CNG cost in fuel compared to an average car?
The EPA estimates that over five years, the 2005 GMC Sierra 2500 HD 2WD CNG will cost about $14,000 more in fuel than an average new vehicle of the same model year. The difference accumulates because the car uses more fuel per mile, not because of any one-off charge at the dealership.
Source: U.S. EPA fuel economy dataset. Annual fuel cost figures assume 15,000 miles of driving per year and a 55% city, 45% highway split. Real-world mileage varies with driving conditions, vehicle maintenance, fuel quality, and driver behaviour.