Spread Between City and Highway EPA MPG

[dalemccl]

The 2006 Vibe base automatic has only a 5 mpg spread between city and highway mpg (29/34). The Corolla automatic with the same engine has a spread of 8 (30/38). The Honda Civic automatic has 10 (30/40). What is the cause of the lower highway mpg in the base Vibe compared to these other cars, when the city EPA is only 1 different (29 vs. 30)?

[prathman]

At least part of the reason might be the aerodynamics, which are more important during highway driving than city. Station wagons are generally less aerodynamic since they generate lots of turbulent airflow behind the rear hatch. The Vibe/Matrix are also quite a bit taller than the Corolla or Civic.(BTW, we averaged almost 41 mpg on a recent road trip of about 8000 miles so the EPA number might be a bit low.)

[SeattleJeremy]

The weight of the car also effects the EPA estimates. The Vibe/Matix is about 150lbs heavier than the Corolla.

[prathman]

Quote, originally posted by Jeremy96gase »The weight of the car also effects the EPA estimates. The Vibe/Matix is about 150lbs heavier than the Corolla.Yes, but extra weight would be expected to have more of an effect on the city mileage due to extra energy needed for accelerating whereas most of the highway cycle is at pretty steady speeds where weight isn't as much of a factor.

[redlava]

Just an idea, not sure if it is right or not. The engines might be tuned differently. They might be the same engine, but they are two different automakers (ie. Gm and Toyota). And Honda has a completely different engine all together.

[ColonelPanic]

Quote, originally posted by redlava »Just an idea, not sure if it is right or not. The engines might be tuned differently. They might be the same engine, but they are two different automakers (ie. Gm and Toyota). And Honda has a completely different engine all together. Good points... I'm wondering what the difference in gearing is between the Corolla and Vibe. If there were differences there, that could have a big impact on what numbers we're seeing.

[joatmon]

the 2006 Matrix auto is rated 28/34.Unless it has changed in the last year, the Corolla/Vibe/Matrix all have the same gear ratios