Are Cars Less Efficient on Asphalt Roads?

As an asphalt construction expert, I’m occasionally asked whether vehicles experience lower fuel efficiency on asphalt pavement compared to concrete roads. This is an insightful question with some nuance. In this article, I’ll provide a definitive answer upfront using a reverse scheme, followed by an in-depth look at the factors that influence fuel economy on various road surface types.

The Short Answer: No Difference in Fuel Efficiency Between Asphalt and Concrete Roads

Rigorous studies by government agencies and universities have proven vehicles achieve essentially equal fuel economy on asphalt and concrete roads when all other conditions are equal. Neither material inherently improves or reduces auto efficiency when pavement quality is maintained. Differences of less than 1% are within the margin of error.

However, several other factors like roughness, texture, congestion, and vehicle speed do impact mileage significantly no matter the surface. Maintaining optimal road conditions minimizes efficiency losses regardless of paving material.

Now that I’ve provided the direct conclusion upfront, let’s examine the details behind fuel economy on asphalt versus concrete highways.

Tire Rolling Resistance

The tire-to-road interface is where fuel efficiency gains or losses occur. As a tire roll, it naturally deforms where it touches the pavement surface. This flexing action requires energy, creating tire rolling resistance.

Rolling resistance reduces mileage since the engine must expend extra fuel to overcome it. Lower tire resistance equals better fuel economy.

For roads, the key factor influencing rolling resistance is texture. Smaller textured surfaces increase flexing compared to smooth roads.

Both rougher concrete and coarser Superpave asphalt mixes create somewhat higher rolling resistance and reduce mileage to a minor degree. But modern smooth asphalt and concrete pavements are engineered for performance and provide similar minimal resistance.

Testing shows rolling resistance differences between standard asphalt and concrete are insignificant – within the margin of repeatability error. Neither material clearly outperforms the other for tire efficiency.

Vehicle Speed and Congestion

While surface type has essentially no impact, vehicle speed and congestion do affect fuel consumption significantly on any pavement:

  • Stop-and-go traffic and congestion in cities decrease mileage substantially compared to steady highway cruising. More acceleration and braking waste fuel.
  • Higher steady speeds on uncongested roads reduce efficiency due to increased air resistance. Driving 75 mph uses over 15% more fuel than 65 mph.
  • Optimal fuel economy is achieved between 45-60 mph on flat, uncongested roads.

These “roadway factors” influence MPG far more than small tire rolling resistance differences between asphalt and concrete surfaces.

Pavement Condition and Texture

Another key factor is pavement texture and smoothness. While texture impacts rolling resistance minimally, segments with roughness, cracking, and deterioration waste substantial fuel:

  • Bumpy and deteriorated roads reduce mileage by forcing tires to flex over dips and rises. Smoothness saves fuel.
  • Texture should be tuned for safety rather than minimized. Appropriate macrotexture prevents hydroplaning.
  • Both materials must be maintained to provide proper ride quality and texture. Proper upkeep is more important than surface type.

Maintaining smooth, safe pavement conditions greatly reduces tire resistance regardless of asphalt or concrete.

Vehicle and Tire Design

Vehicle design factors like weight, aerodynamics, and transmission tuning affect efficiency far more than road surfaces.

Tire choices also influence fuel economy to a much larger degree. Proper inflation pressures help minimize rolling resistance substantially.

Overall, the vehicle and tires themselves offer greater efficiency opportunities than trying to choose between asphalt or concrete roads.

In summary, while tire rolling resistance differs slightly between pavement types, real-world fuel economy remains identical when properly accounting for other overwhelming factors.

Asphalt vs Concrete Comparison

Here is a comparison highlighting the near-equal efficiency:

Factor Asphalt Concrete
Rolling Resistance Minimal Minimal
Speed/Congestion Impact Same Same
Condition/Texture Impact Same Same
Vehicle Design Impact Same Same

Assuming comparable pavement quality and traffic conditions, vehicles will achieve effectively identical fuel efficiency on properly maintained asphalt and concrete roads.

Now that we’ve covered the key technical points, let’s briefly discuss common misperceptions.

Addressing Misconceptions

Despite the proven equal efficiency, some misconceptions still exist that concrete inherently improves fuel economy:

  • False assumptions that smoother concrete reduces rolling resistance. Both offer minimal resistance when smooth.
  • Anecdotal observations without accounting for texture, speed, or congestion factors.
  • Aggregation bias from combining data not normalized for key variables.
  • Generalizations that All concrete is smoother than asphalt. In reality, both get rough with poor maintenance.

Rigorous controlled studies accounting for all variables consistently show no measurable difference in fuel efficiency between asphalt and concrete pavements.

Why would roads impact fuel efficiency?

The tire rolling resistance caused by the road’s texture and smoothness can create slight increases or decreases in engine effort and mileage. But surface type itself has minimal influence when properly maintained.

What provides the best fuel economy – asphalt or concrete?

Extensive testing shows vehicles achieve the same fuel efficiency on asphalt and concrete when comparing surfaces of equivalent texture and smoothness. Maintaining quality pavement provides maximum efficiency regardless of material.

Do tire wear differences between asphalt and concrete affect efficiency?

Minimal. Tire wear rates between comparable asphalt and concrete roads differ by such small amounts that any efficiency impact would be insignificant – well under 1%.

Does asphalt absorb more fuel or energy from cars than concrete?

No. Differences in heat absorption between asphalt binder and concrete are trivial relative to the amount of fuel energy used by vehicles. It has no measurable effect on fuel economy.

Can switching from asphalt to concrete roads improve MPG?

No, vehicles will achieve essentially the same mileage on properly maintained asphalt and concrete surfaces. Switching materials provides no real-world fuel efficiency improvements.

While road surface type has no significant bearing, proper maintenance providing smooth, safe pavement maximizes fuel economy regardless of asphalt or concrete. Their equal efficiency allows for choosing the ideal material for conditions and total value. Please let me know if you have any other asphalt road questions!

Was this article helpful?
YesNo

I'm Steve Axton, a dedicated Asphalt Construction Manager with over 25 years of experience paving the future of infrastructure. My journey with asphalt began by studying civil engineering and learning about core pavement materials like aggregate, binder and additives that compose this durable and versatile substance. I gained hands-on experience with production processes including refining, mixing and transporting during my internships, which opened my eyes to real-world uses on roads, driveways and parking lots. Over the past decades, I have deepened my expertise in asphalt properties like viscosity, permeability and testing procedures like Marshall stability and abrasion. My time with respected construction companies has honed my skills in paving techniques like milling, compaction and curing as well as maintenance activities like crack filling, resurfacing and recycling methods. I'm grateful for the knowledge I've gained about standards from Superpave to sustainability best practices that balance longevity, cost and environmental friendliness. It's been an incredibly rewarding career working with this complex material to build the infrastructure future.

Leave a Comment