Commuting can be a significant part of daily life, and for those with long distances to travel, efficiency becomes paramount. One user on a car enthusiast forum, facing a 180-mile daily commute, raised a compelling question: disregarding typical advice to slow down for fuel economy, what car delivers the Best Mpg Car at a constant speed of 90mph? This is a pertinent question for those who value time and need to cover ground quickly without excessive fuel consumption. Let’s delve into the expert opinions and suggestions from the forum to uncover the vehicles that might offer the most miles per gallon at this elevated speed.
Understanding fuel efficiency at high speeds is crucial. Aerodynamic drag increases exponentially with speed, meaning that maintaining 90mph requires significantly more power than lower speeds. This increased power demand directly translates to higher fuel consumption. Therefore, cars designed with aerodynamic efficiency in mind, along with engines optimized for cruising at higher revolutions, are likely contenders for the best MPG car in this scenario.
Several suggestions emerged from the forum discussion, pointing towards different types of vehicles and technologies. Let’s explore the most prominent recommendations for achieving optimal MPG at 90mph:
Aerodynamics is Key:
Many experts in the forum emphasized aerodynamics as the primary factor influencing fuel economy at 90mph. Cars with a low drag coefficient (Cd) and a small frontal area will cut through the air more efficiently, requiring less engine power to maintain speed.
-
Tesla Model S: The Model S was repeatedly suggested as a top contender. Electric vehicles, in general, can be efficient at higher speeds due to their instant torque and smooth power delivery. The Model S, specifically, is designed with aerodynamics in mind.
-
Honda Insight: This hybrid vehicle, known for its aerodynamic shape and fuel-efficient engine, was also recommended. Its design philosophy prioritizes minimizing drag to maximize MPG.
-
Mazda 3 Sedan (Current Gen): Highlighted for its low drag coefficient of 0.26, the Mazda 3 sedan, particularly with its high-compression 2.0 engine, is considered a strong option for highway fuel efficiency.
Diesel (TDI) Considerations:
Diesel engines, especially older TDI models, were brought up as potential solutions. Diesel engines often offer better fuel economy at cruising speeds due to their higher energy density fuel and different combustion characteristics.
- Older TDI Models (1999-2003 ALH Engine): These older Volkswagen TDI engines are known for their impressive fuel economy. Some forum members suggested that with modifications like a 5th gear swap and aerodynamic enhancements, these cars could potentially achieve MPG figures in the 50s at 85-95mph. However, maintenance costs for older vehicles need to be considered.
Alt text: Image of a 2003 Volkswagen Jetta TDI, a suggested model for high MPG at 90mph due to its ALH diesel engine.
Plug-in Hybrids: A Mixed Bag?
Plug-in hybrids like the Chevrolet Volt and modified Prius were mentioned, but with caveats regarding battery depletion at high speeds and sustained inclines.
-
Chevrolet Volt: The Volt could offer gas-free driving for a portion of the commute if the battery range suffices for part of the 180-mile journey. However, real-world MPG at 90mph and battery depletion rates need to be carefully evaluated.
-
Modified Prius: While the original poster was already driving a Prius and achieving 36 MPG at 90mph, suggestions included adding battery packs or plug-in hybrid kits to enhance electric range. The Prius, being inherently aerodynamic, serves as a decent baseline, but its hybrid system might be less effective at constant high speeds with inclines.
Motorcycle as an Alternative:
An unconventional but practical suggestion was a sport-touring motorcycle. Motorcycles, being inherently lighter and more aerodynamic than cars, can achieve excellent fuel economy even at higher speeds. Many sport-touring bikes can deliver over 40 MPG and are designed for comfortable high-speed cruising. However, this depends heavily on weather conditions and personal preference for motorcycle commuting.
Factors Beyond Car Choice:
The forum discussion also touched upon factors beyond just the car model:
-
Aerodynamic Modifications: Improving the aerodynamics of an existing car, even a Prius, can yield noticeable MPG gains at 90mph. This could involve modifications like wheel covers, underbody panels, and streamlining elements, although some may affect aesthetics.
-
Tire Choice: Low rolling resistance tires can contribute to better fuel economy, although their impact might be less significant at 90mph compared to lower speeds.
-
Engine and Gearing: Engines designed for higher RPM cruising and appropriate gearing are crucial for efficiency at 90mph. Turbocharged engines might not be ideal as they could be operating in boost range at these speeds, reducing MPG.
Is 36 MPG at 90mph Good?
The original poster’s 36 MPG in a Prius at 90mph was considered by many forum members to be quite respectable. At such a high constant speed, aerodynamic drag becomes a dominant force, and achieving significantly higher MPG without substantial vehicle modifications or switching to a different vehicle type might be challenging.
Conclusion:
For those seeking the best MPG car for a 90mph commute, aerodynamic efficiency is paramount. Electric vehicles like the Tesla Model S and aerodynamically designed hybrids like the Honda Insight are strong contenders. Older diesel TDI models, with potential modifications, might also offer competitive MPG, but require careful consideration of maintenance. While the Prius already achieves a decent 36 MPG at 90mph, further gains could be incremental without significant changes. Ultimately, the “best” car depends on individual priorities, budget, and willingness to consider modifications or alternative vehicle types like motorcycles. For maximizing fuel economy at a consistent 90mph, focusing on vehicles engineered for minimal aerodynamic drag and efficient high-speed cruising is the most effective approach.
