20 MPG combined won’t set any fuel economy records, but for the 2015 Chevrolet Impala Bi-Fuel (CNG) 3.6L 6-cyl, that’s not the main point. This vehicle is designed to offer a cost-effective transportation solution for fleet customers or extremely high-mileage drivers with consistent access to compressed natural gas. This isn’t the Impala families choose for style; businesses select it to significantly lower their fueling bills per mile. Its appeal is tied to the economic benefits of CNG, trading gasoline efficiency for lower fuel costs.

City and highway performance

The EPA estimates for the 2015 Impala CNG are 17 MPG in the city and 25 MPG on the highway. These numbers reflect operation on CNG, not gasoline. The drop in fuel economy is expected due to the lower energy density of compressed natural gas compared to gasoline. This is less crucial for consumers focused on the lower overall fuel cost; fuel price is the driving factor.

Annual fuel cost

The EPA calculates the estimated annual fuel cost of the 2015 Chevrolet Impala Bi-Fuel (CNG) at $2,200. This figure is based on driving 15,000 miles per year, with a mix of city and highway driving, and using the national average fuel price at the time of the EPA’s testing. This annual cost assumes using compressed natural gas. CNG prices can fluctuate significantly depending on location and availability, so you should consider local CNG costs when evaluating potential cost savings. If the vehicle uses gasoline, the annual fuel cost will be significantly higher due to poorer MPG.

Real-world expectations

Real-world MPG for the Impala CNG can vary considerably based on driving style, terrain, and driving conditions. Expect figures closer to the 17 MPG city estimate or even lower if driven primarily in stop-and-go traffic. Consistent highway driving may yield numbers closer to, or even slightly above, the 25 MPG highway estimate. Fleet managers who prioritize smooth acceleration and consistent speeds will likely see the best fuel economy.

The availability of CNG fueling stations also determines whether the lower per-mile cost is worth the tradeoff. Some of the expected savings will be lost if drivers must travel considerable distances to fuel up.

How it compares

The CNG version’s 20 MPG combined is less than the standard gasoline-powered 2015 Chevrolet Impala, which achieves around 22 MPG combined. The standard 3.6L V6 gasoline model achieves around 22 MPG combined, however the comparison is about the cost per mile. The Toyota Avalon, another large sedan competitor, achieves around 24 MPG with its gasoline-powered versions. Even hybrid versions of other large sedans offer better fuel efficiency, like the Ford Fusion Hybrid that achieves 42 MPG. Even with those higher MPG figures, the economics of using CNG can still mean lower per-mile expenses, which is why the Bi-Fuel Impala exists. Fleet buyers shopping vehicles like the Impala will review all Chevrolet fuel economy data, and carefully analyze the fuel cost differences for their specific use cases.

Tips to maximize efficiency

Aggressive acceleration and hard braking negatively affect fuel economy, regardless of the fuel source. Maintaining a smooth and steady driving style can improve MPG. Anticipating traffic flow and avoiding sudden stops can lead to savings in the Impala CNG. The driving range is limited by the size of the CNG tank, so optimizing fuel efficiency becomes more urgent.

Tire pressure is another factor that affects fuel economy. Ensure tires are properly inflated to the recommended pressure on the door jamb sticker. Underinflated tires increase rolling resistance, which forces the engine to work harder and consume more fuel. This simple maintenance task can affect MPG, even on an IMPALA MPG across all years.

Proper vehicle maintenance is critical for maintaining fuel economy. Regular oil changes, air filter replacements, and spark plug replacements ensure the engine operates efficiently. A well-maintained engine runs smoother and requires less fuel to produce the same amount of power. Ignoring routine maintenance can lead to decreased performance and reduced fuel economy.

Plan routes to minimize stop-and-go traffic whenever possible. Idling consumes fuel without covering any distance, so avoiding congested areas can improve overall fuel economy. Using navigation apps to identify the most efficient route can save time and fuel. This is important for CNG vehicles because the need to make fueling stops has a greater potential to affect the overall trip time.