What controls Highway vs. City mileage?

I have owned my 1995 Toyota 22-RE 1/2 ton pickup (not Tacoma) for over 6 years. I record MPG religiously (my wife thinks I’m crazy), and in this truck it rarely changes much, except dropping some during cold periods as expected.



But, our relatively new (to us) '03 Subaru Outback 4 cyl. is sensitive to City vs. Highway driving with regard to MPG. Highway is good at around 28-29, but “city” (we’re in a rural place with few traffic lights) is always 2-3 MPG lower.



I’m curious as to what causes the difference in response to driving conditions RE: MPG. Is it the AWD?

First, AWD is heavier than a two wheel drive. Second, city driving is a lot of stop and go even if it may be street stop signs. Getting something to move from a dead stop takes more power than if one was coasting up to a stop light. Finally, MPG will really depends on the car, manufacturer etc.

The Subie is a whole different vehicle with a different torque curve, different gearing, different tires, different engine, different everything. It’s not realistic to compare the two. There’s 1,000 things different that could in combination or individually affect the question.

And, let’s not forget that the driver controls the mileage to some extent. Taking short trips for local errands will kill gas mileage very quickly, as will idling at drive-up windows for banks, fast food joints, etc.

That being said, if the OP is experiencing gas mileage that is only 2-3 mpg lower for urban driving as opposed to highway driving, he is actually doing pretty well.

It’s simple, really. On the highway you’re almost always moving, so the vehicle is getting “some” mile out of each gallon. Sitting still with the engine running at traffic lights or stop signs in the city yields ZERO mpg. And those times of 0 mpg add up to reduce the mileage you would otherwise have gotten.

Wind resistance and speed play a big roll on the highway, but you have very little time at 0 mpg. You’ll get better mileage at 55 mph than at 75, but either is likely to be higher than strictly city driving (unless you’re in a Prius).

I once had a Ford Crown Victoria that got 17.5 mpg no matter where or how I drove it. City, highway, fast, or slow; 17.5 mpg almost every tankful.

Both my Subaru and my Acura, however, get anywhere from 4 to 7 mpg more on the highway than they do in town.

Why the difference with the two vehicles?

I suspect the truck was geared for more weight or towing and you did not do much of either. That low gearing tends to do two things. First it means less of a penalty for starting up from the stop to driving speed and it reduces the highway mileage.

Thanks Joe. This is what I was looking for. I was aware of all the many driver-related things that can affect MPG. I was curious about the different responses from the two diff. vehicles.

The fact that you’re moving in a HIGHER gear on the highway is ONE reason you get better gas mileage. And also in city traffic you do a lot of idling. When you car idles…you get 0mpg.

I had a similar pickup, a 1987 Mazda B-2000 extended cab that got 24 locally and 25 highway. Neat trick.

it would also depend on the engines in each vehicle. are both four cyl?

do you drive one, and the better half drives the other?

do you typically drive different distances with the two cars? (for example you drive the truck 30 miles each day to work, and the wife drives 4 miles?)