Heavy city traffic representing stop-and-go driving that can reduce fuel economy

Stop-and-Go Traffic and MPG: What You Can (and Can’t) Control

February 23, 2026 9 min read

Quick Summary Stop-and-go traffic often lowers MPG because it involves repeated acceleration and braking and often increases time spent idling. DOE and AFDC fuel-economy guidance highlights that aggressive acceleration/braking and unnecessary idling waste fuel. You can’t control congestion, but you can control your following distance, how smoothly you accelerate, and how you plan trips.

Repeated acceleration/braking and idling increase fuel used per mile.
Smooth driving habits can reduce waste in traffic (AFDC, DOE).
Trip planning and combining errands can reduce exposure to congestion.

What We Know (Sourced)

DOE’s fuel-saving guidance highlights that aggressive driving (rapid acceleration and braking) can reduce fuel economy and that avoiding unnecessary idling can save fuel. Source: DOE — Driving More Efficiently.

AFDC summarizes efficient driving behavior techniques that conserve fuel, emphasizing smoother driving habits. Source: AFDC — Efficient Driving to Conserve Fuel.

Why Stop-and-Go Hurts MPG

Stop-and-go driving tends to hurt fuel economy because:

Acceleration costs fuel. Repeatedly speeding up after braking increases fuel burned.
Braking wastes momentum. Hard braking forces the vehicle to spend more energy to regain speed.
Idling adds time with 0 MPG. If you idle a lot in congestion, you burn fuel without moving.

If you want to understand idling specifically, see: Idling fuel use. If your city driving is the majority of your miles, the label’s City MPG will often be more relevant than Highway MPG (see: Highway vs City MPG).

What You Can Control (Safe)

You can’t control traffic volume, but you can reduce fuel waste with safe habits:

Increase following distance so you can coast instead of brake hard.
Accelerate smoothly rather than “sprinting” to the next stop.
Plan around known bottlenecks when possible.

Safety first: Don’t try unsafe tactics (tailgating, drafting, weaving) to save fuel. Smoothness comes from space and patience, not risk.

What to Do Next

If congestion is a big part of your commute, the most reliable “next steps” are:

Combine errands to reduce total trips and cold starts: Combine errands to save fuel.
Keep maintenance tight so efficiency losses don’t stack (see: tire pressure and fuel economy).
Estimate your baseline so you can see whether changes matter financially.

Estimate the Cost for Your Commute

Traffic makes fuel cost unpredictable because MPG varies with time spent stopped. You can still budget by using a conservative MPG estimate and your typical miles. Try:

Estimate Your Monthly Commute Fuel Cost

Use miles, MPG, and gas price to estimate weekly and monthly fuel spending.

Use the Commute Gas Cost Calculator

Frequently Asked Questions

Why does my dashboard MPG drop so much in traffic?

Traffic increases time spent idling and the number of acceleration/braking events, both of which can increase fuel used per mile.

Is there a “best” route for MPG?

Often the best route is the one with fewer stops and less congestion, even if it’s slightly longer. Testing a couple of routes and comparing average MPG over a week is usually the best way to know for your commute.

Does turning the engine off at long lights save fuel?

DOE provides guidance on idling and a rule of thumb for when turning the engine off can save fuel. See: DOE — Driving More Efficiently.

What’s the fastest way to budget fuel cost with traffic?

Use a conservative MPG estimate (slightly lower than your best-case) with your weekly miles and gas price. Our Commute Gas Cost Calculator makes this easy.