Would like higher MPG....2010 Civic advice
 

Okay almost made a week on a tank of gas. I travel 100 miles a day, 1.8 motor, automatic. The roads are 4 lane mostly and speed is 70 MPH. I filled up tonight and only got 33.5 MPG. I do drive 70 when possible, started coasting when time to turn, not needing brakes, use the cancel on the cruise instead of tapping the brake. I go easy after a highway turn to get back up to speed so very little shifting happening. Anyway thats all I learned this week but I am hoping someone can tell me the sweet spot maybe for best economy on highway. Maybe I need to start there.

Your sweet spot for cruising is probably under 60 mph. What's your tire pressure?

Unfortunately, having an automatic transmission might be somewhat limiting.

I have not checked them but I would guess around 35. I like to run max tire pressure and synthetic oil and I will at the first oil change. I calulated my daily GPD (gallons per day)and it came to 2.4. That sure sounds real good to me for 100 mile a day comutte.

Driving that fast is pretty hard on gas mileage. I understand commute time is a factor as well, but the more you can slow down, the more it will help your mileage. The sweet spot for steady state driving is the minimum speed you can maintain in your top gear. I'm guessing 35 or 40 wouldn't be too safe (or legal) with a 70 mph speed limit.

Along the same lines, aerodynamic improvements may have a bigger impact for you than most others here. Air drag increases significantly at those speeds.

Get a ScanGauge or an UltraGauge. It will pay for itself in what it teaches you about your driving style. As others are saying above: slow down a little, pump up the tires, look into aeromods. You should at minimum set your tires to the max psi written on the side of the tire. Doing the tires and slowing down to 60 would bring you a few MPG starting tomorrow morning. Good luck.

What the others said about slowing down.
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Slow down a bit.
To 65 mph, maybe even 60 mph.

50 miles at 70 is 0.71 hours
50 miles @ 60 is 0.83 hours, 0.12 hours longer, that's 7 minutes.
Chances are you won't see a 7 minute increase in your commute as your average speed doesn't necessarily need to go down by slowing down - you're probably not always doing 70.

Increasing the tyre pressure will also help - keep an eye on tyre wear.
(Though higher pressure has actually evened out the uneven shoulder-wear on my tyres ;) )

Blocking the upper grille will also help a bit - better aerodynamics, somewhat faster warm-up - though keep an eye on the engine temperature.
Make an easily removable "proof of concept" just in case the engine starts running too hot. Cardboard or some stiff plastic will do as a try-out, doesn't need to be neat.

Remove all unnecessary weight from the car.
Many have also removed their spare tyre and jack.

Those are the most common modifications people here do, aside from adjusting their driving style.

I'd second getting instrumentation (SG or UG). With as many miles as you're traveling, it'll pay for itself in no time.

I'd also look into slowing down a little more. Most of us here notice if you go just a little bit slower you tend to upset people. If you slow down a little more they're much more apt to just go around you.

I would definitely put at least an upper grill block on right away, and start looking into other aeromods that you feel comfortable doing.

I'm stuck with an automatic vehicle, too. That said, my MPG went from about 28.5 pre-ecomodder to 33 presently (average since joining). (I'd like to get that higher, but winter is bogging me down.)

Reiterating others tips, consider a scangauge and an upper grill block. The scangauge helped me learn the 'sweet spots,' which happened to be between 35-65 mph. This is also the range in which my DFCO (Direct Fuel Cutoff) functions. VERY good for mileage. Good luck.

I have been studying the subject of how to improve fuel mileage for about 12 years now and I can honestly say that in all of that time I have found the two most important things one can do while keeping safety and practicality in mind...

Are a light foot on the throttle.
And stop anticipation.

A lot of everything else is mere obsession bordering on compulsive and disorderly behavior that, while it results in a fuel economy gain does not result in a net gain.

If the tires are wearing faster because you are improving fuel economy you're not winning, and if your safety or the safety of other drivers is put at risk because of obsessive behavior concerning the all mighty fuel economy, still nobody wins.

Shortly after I would strongly recommend doing all the regular maintenance such as keeping up on the oil changes and making sure the plugs / wires / cap+rotor are good, also tire pressure all around is very important.

But there is little argument, if you have a lead foot you need to lighten up on the throttle, you argue on the one hand that you want to see better fuel economy, yet on the other you throw it in my face that you're going to drive 70!
Well, there you have it.

Your driving 64 in that 70mph zone would help considerably, you'd see a 10% improvement there alone.
Stop taking those turns, you're simply shaving about 20 thousand miles off your tires.
Instead try anticipating stops and coasting into them.

Most everything else either compromises safety or we end up paying for it some other way, you do realize taking turns hard wears out that $400 set of tires...
Not to mention it is dangerous.
This is what happens when we so concentrate on fuel economy we simply place the burden elsewhere.

There is no argument, if you have a lead foot you need to lighten up on the throttle.