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Calculate MPG, cost per mile, fuel consumption rates, and compare vehicle efficiency to optimize fuel spending.
25.7 MPG
US avg (2023)
$3.40/gal
US avg regular
~$2,400
Annual fuel cost
15,000 mi
Avg annual miles
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Gas mileage (fuel economy) measures how efficiently a vehicle converts fuel into distance traveled. In the United States, it's expressed as miles per gallon (MPG) — the higher the number, the more efficient the vehicle. Most other countries use liters per 100 kilometers (L/100 km), where a lower number indicates better efficiency.
The average new car sold in the U.S. in 2023 achieved 25.7 MPG combined (city + highway), according to the EPA. This represents a significant improvement from 20.0 MPG in 2004, driven by federal CAFE (Corporate Average Fuel Economy) standards, turbocharging, direct injection, hybrid drivetrains, and lightweight materials.
The two most important factors affecting your real-world MPG are driving behavior (aggressive acceleration reduces fuel economy by 15-33%) and speed (every 5 mph above 50 mph costs roughly an extra $0.20 per gallon). Tire pressure, vehicle maintenance, AC usage, cargo weight, and weather also significantly impact fuel consumption.
MPG = Miles Driven ÷ Gallons Used Example: 350 miles on 14.2 gallons MPG = 350 ÷ 14.2 = 24.6 MPG Combined MPG (EPA method): 1/Combined = 0.55/City + 0.45/Hwy Example: 28 city / 36 highway 1/Combined = 0.55/28 + 0.45/36 = 0.01964 + 0.01250 = 0.03214 Combined = 1 / 0.03214 = 31.1 MPG Note: EPA combined weights 55% city and 45% highway to reflect typical American driving patterns.
Track MPG by recording odometer and gallons at every fill-up. Consistency over multiple tank-fulls gives the most accurate picture.
L/100km = (Liters Used ÷ km) × 100 Convert MPG → L/100km: L/100km = 235.215 ÷ MPG Convert L/100km → MPG: MPG = 235.215 ÷ L/100km Examples: 30 MPG = 235.215 ÷ 30 = 7.84 L/100km 6 L/100km = 235.215 ÷ 6 = 39.2 MPG Imperial (UK) gallons: MPG(UK) = MPG(US) × 1.20095 30 US MPG = 36.0 UK MPG Note: UK gallon = 4.546 L (larger than US gallon = 3.785 L).
When reading European or Canadian fuel economy specs, they use L/100km. UK often uses MPG but with larger imperial gallons — don't confuse with US MPG.
Cost Per Mile ($): = Gas Price ÷ MPG Annual Fuel Cost ($): = (Annual Miles ÷ MPG) × Gas Price Example: 25 MPG, $3.50/gal, 15,000 mi/yr Cost/mile = $3.50 ÷ 25 = $0.14 Annual = (15,000 ÷ 25) × $3.50 = 600 gallons × $3.50 = $2,100 Comparison: 35 MPG vs 25 MPG 35 MPG: 15,000 ÷ 35 = 429 gal = $1,500 25 MPG: 15,000 ÷ 25 = 600 gal = $2,100 Annual savings: $600 (29% less) EV equivalent: 30 kWh/100mi × $0.16 = $0.048/mi vs gasoline at 25 MPG: $0.14/mi
| Vehicle Type | City MPG | Highway MPG | Combined MPG | Annual Fuel* |
|---|---|---|---|---|
| Compact sedan | 30–35 | 38–44 | 33–39 | $1,300–$1,550 |
| Midsize sedan | 28–32 | 36–42 | 31–36 | $1,400–$1,650 |
| Full-size sedan | 24–28 | 32–38 | 27–32 | $1,600–$1,900 |
| Compact SUV | 26–30 | 32–38 | 28–33 | $1,550–$1,800 |
| Midsize SUV | 22–26 | 28–34 | 24–29 |
| Fuel Type | Unit Price | Energy / Unit | Cost per 100 mi | Annual Cost* |
|---|---|---|---|---|
| Regular (87 oct) | $3.40/gal | 33.7 kWh/gal | $13.60 (25 MPG) | $2,040 |
| Premium (93 oct) | $4.00/gal | 33.7 kWh/gal | $16.00 (25 MPG) | $2,400 |
| Diesel | $3.80/gal | 37.9 kWh/gal | $15.20 (25 MPG) | $2,280 |
| E85 (Flex fuel) | $2.80/gal | 26.5 kWh/gal | $14.74 (19 MPG) | $2,211 |
| Electricity (home) | $0.16/kWh | 1 kWh |
Use cruise control on highways. Every 5 mph above 50 costs ~$0.20/gallon extra.
Gradual acceleration and braking dramatically improve city MPG. Coast to red lights.
Under-inflated tires increase rolling resistance. Every 1 PSI drop costs ~0.2% MPG.
An extra 100 lbs in trunk reduces MPG by ~1%. Clean out unnecessary cargo.
Premium fuel doesn't help engines designed for regular. Only use premium if required by manufacturer.
1908
The Ford Model T gets approximately 13-21 MPG. With gasoline at $0.18/gallon, fuel economy wasn't a concern for early motorists.
1973
The OPEC oil embargo causes gas prices to quadruple overnight. Long lines at gas stations spark national urgency for fuel-efficient vehicles.
1975
Congress passes the Energy Policy and Conservation Act, establishing CAFE (Corporate Average Fuel Economy) standards — requiring automakers to achieve 18 MPG by 1978, rising to 27.5 MPG by 1985.
1993
The EPA introduces the current fuel economy testing procedure, replacing the overly optimistic 1975 test cycle. This results in more realistic (lower) MPG numbers on window stickers.
2007
The Energy Independence and Security Act raises CAFE targets to 35 MPG by 2020. This accelerates development of hybrids, turbo engines, and lightweight materials.
2012–present
Obama-era rules target 54.5 MPG by 2025 (later relaxed to ~40 MPG). EV sales accelerate, reaching 9% of new US car sales in 2023. The EPA introduces MPGe ratings for electric vehicles.
Official US government source for MPG ratings on every vehicle sold since 1984. Compare vehicles, calculate fuel costs, and find the most efficient models in each class.
Visit EPA Fuel Economy Guide (fueleconomy.gov) →Comprehensive data on alternative fuel prices, station locations, vehicle availability, and fuel cost comparisons across gasoline, diesel, electricity, hydrogen, and CNG.
Visit DOE Alternative Fuels Data Center →The definitive reference for US transportation energy statistics: fleet fuel economy trends, fuel consumption by vehicle type, and historical efficiency data since 1960.
Visit Oak Ridge National Laboratory — Transportation Energy Data Book →The International Council on Clean Transportation researches the gap between laboratory fuel economy ratings and real-world driving. Studies show a 25-40% gap in Europe and 10-20% in the US.
Visit ICCT — Real-World Fuel Economy Gap →MYTH
Premium gasoline gives better gas mileage in any car.
FACT
Premium fuel only benefits engines specifically designed for it (high-compression or turbocharged engines that require 91+ octane). In a regular car, premium fuel provides zero MPG improvement — you're just paying 15-20% more per gallon for no benefit.
MYTH
Warming up your car for 5-10 minutes improves fuel economy.
FACT
Modern fuel-injected engines need only 30-60 seconds of idle time even in cold weather. Idling for 10 minutes wastes 0.1-0.2 gallons and produces unnecessary emissions. The fastest way to warm your engine is to drive gently.
MYTH
Manual transmissions always get better gas mileage than automatics.
FACT
This was true decades ago, but modern automatic transmissions with 8-10 speeds and torque converter lock-up often match or exceed manual MPG. CVTs (continuously variable transmissions) in hybrids are among the most efficient.
MYTH
Opening windows is always more fuel-efficient than using AC.
Fill your tank completely, reset or note your trip odometer, drive normally until near empty, refill and note the gallons added. Divide miles driven by gallons used. For accuracy, average at least 3 full tanks.
City MPG accounts for stop-and-go driving with frequent braking and acceleration. Highway MPG reflects steady-speed cruising. Highway MPG is typically 20-40% higher because constant speed is more fuel-efficient.
Most vehicles reach peak fuel efficiency at 35-50 MPH. Above 50 MPH, aerodynamic drag increases exponentially. Each 5 MPH increase above 50 costs roughly $0.20 more per gallon — driving 70 vs 55 can reduce MPG by 15-25%.
MPGe (miles per gallon equivalent) converts electric energy to a gasoline equivalent using 33.7 kWh = 1 gallon. A 100 MPGe EV travels 100 miles on the same energy as 1 gallon of gas, making it 3-4x more energy-efficient.
Calculate MPG, compare fuel costs, and discover proven strategies to improve your vehicle's fuel economy.
Try the Gas Mileage Calculator →Last updated:
When comparing vehicles, annual fuel cost matters more than MPG. Going from 15 to 20 MPG saves more money than going from 35 to 50 MPG for the same annual miles.
Trip Fuel Cost ($): = (Distance ÷ MPG) × Gas Price Tank Range (miles): = Tank Size × MPG Example: 400-mile road trip, 28 MPG Gallons needed = 400 ÷ 28 = 14.3 Cost at $3.50/gal = $50.00 Tank range: 15-gal tank, 28 MPG Range = 15 × 28 = 420 miles Safe range (leave 10%) = 378 miles Round-trip cost: 800 miles ÷ 28 MPG = 28.6 gallons 28.6 × $3.50 = $100.00 Split between passengers: 4 passengers: $25.00 each vs. flying: ~$200+ per person
Always calculate fuel costs BEFORE road trips. For long trips, compare driving cost (fuel + tolls + wear) vs flying or train — driving is usually cheaper for 2+ passengers.
| $1,750–$2,150 |
| Full-size SUV / truck | 16–20 | 22–28 | 18–23 | $2,200–$2,850 |
| Hybrid sedan | 48–58 | 44–52 | 46–55 | $700–$900 |
| Hybrid SUV | 38–44 | 36–40 | 37–42 | $950–$1,100 |
| Plug-in hybrid | 80–120 MPGe | 35–42 gas | 50–80 actual | $500–$900 |
| EV (no gas) | 100–140 MPGe | 90–120 MPGe | 95–130 MPGe | $450–$700† |
| Diesel truck | 18–22 | 24–30 | 20–25 | $2,000–$2,500 |
| Motorcycle | 40–60 | 50–70 | 45–65 | $700–$1,000 |
*At $3.40/gal, 15,000 mi/year. †EV cost based on $0.16/kWh average. MPGe = miles per gallon equivalent (33.7 kWh = 1 gallon). Ranges reflect 2023-2024 model averages.
| $4.80 (30 kWh) |
| $720 |
| Electricity (DC fast) | $0.40/kWh | 1 kWh | $12.00 (30 kWh) | $1,800 |
| Hydrogen (FCEV) | $16/kg | 33.3 kWh/kg | $24.24 | $3,636 |
| CNG | $2.50/GGE | 33.7 kWh/GGE | $10.00 (25 MPGGE) | $1,500 |
*Based on 15,000 mi/year. GGE = gasoline gallon equivalent. Prices are US national averages (2024). Actual costs vary by region and vehicle efficiency.
Several short cold-start trips use more fuel than one multi-stop trip. Engines are most efficient when warm.
FACT
Below 40-45 MPH, open windows are more efficient. Above that speed, the aerodynamic drag from open windows actually uses MORE energy than the AC compressor. On the highway, use AC; in city driving, open the windows.
MYTH
Smaller cars always get better gas mileage than larger cars.
FACT
Vehicle size is only one factor. A modern midsize turbocharged sedan (35 MPG) can beat a poorly designed compact (28 MPG). Aerodynamics, engine technology, weight, and drivetrain design matter as much or more than overall size.
MYTH
Fuel additives and 'MPG boosters' significantly improve fuel economy.
FACT
The FTC and EPA have tested hundreds of aftermarket MPG-improvement products. None have been proven to improve fuel economy by more than 1-2%. The best 'fuel saver' is gentle driving, proper tire pressure, and regular maintenance.
Yes, AC compressors typically reduce MPG by 5-15% depending on the system and driving conditions. However, at highway speeds (45+ mph), AC is more efficient than open windows due to reduced aerodynamic drag.
Every 1 PSI drop in tire pressure decreases MPG by approximately 0.2%. Under-inflation by 10 PSI on all four tires can cost 3-4% MPG. Check tires monthly when cold — tire pressure drops ~1 PSI per 10°F temperature decrease.
In modern fuel-injected cars, engine braking (in gear, foot off gas) uses ZERO fuel — the injectors shut off completely. Coasting in neutral uses idle fuel. In-gear coasting is both more fuel-efficient and safer.
Divide 235.215 by the MPG value: 30 MPG = 235.215 ÷ 30 = 7.84 L/100km. Reverse: 235.215 ÷ L/100km = MPG. Note: UK MPG uses imperial gallons (4.546 L), while US MPG uses US gallons (3.785 L).
Yes. Ethanol has ~33% less energy per gallon than gasoline. E10 (standard US gas) reduces MPG by ~3%. E15 reduces by ~5%. E85 (flex fuel) reduces by 20-30% but is usually priced 15-25% cheaper per gallon.
Going from 20 MPG to 30 MPG saves 250 gallons/year (at 15,000 miles). At $3.50/gallon, that's $875/year — $4,375 over 5 years. The MPG improvement from 15→20 saves more than 30→50 due to the non-linear nature of fuel consumption.
Hypermiling is a set of driving techniques to maximize fuel economy: steady speed, gentle acceleration, anticipating traffic, minimizing braking, maintaining tire pressure, and reducing vehicle weight and drag. Practitioners routinely achieve 20-50% above EPA ratings.
EPA tests are conducted in a laboratory on a dynamometer under controlled conditions. Real-world factors — aggressive driving, short trips (cold engine), AC, cargo, hills, wind, rain, and tire condition — typically reduce MPG by 10-20% below the sticker value.