Okay, so I've been driving to work for the past month, getting on average 41-43 MPG. I drive 71 MPH with CC on the whole time. So I decided to do a test this last week, and have been driving at 65MPH and Im only recieving a .5MPG boost.
I drive roundtrip 135 miles. Anyone have any assistance? Thanks!

 

James,

What sort of terrain are you driving in (flat , moderate hills, very hilly)? If you are driving in anything other than rather flat terrain, the cruise control will hurt mileage. Give us a bit more information on the drive? Is it all highway? Is there stop and go driving before the car is warmed up? What is the temperature like? Any rain? Tire pressure?

Eric

 

Yeah sorry, Im at work right now and had to make a quick post. Anyways, the terrain is hilly both ways. About 55 out of the 65 miles is highway. I do about .5 miles of stop and go traffic in between (switching highways in a small town). Temperature is mid 40's -50's in the morning (North East part of the country). Lots of Stop and Go traffic early in the morning. I haven't touched tire pressure since I purchased it (less than a month so far) I only have 2500 miles on it also. I haven't tried really not using the CC at all, so my MPG are based entirely upon CC. I love the car beyond belief, but my wife is pissed that we spent so much money on a vehicle that gets barely 10 more MPG than my old vehicle.

 

Don't forget you are still in the break-in period for the car. You should notice an improvement during the 3-5k mile period.

Check the tire pressure. You can run the Bridgestones at 44 and the Dunlops at 51 psi. (Check your tires to be sure, your results may vary, void where prohibited ).

Welcome to Greenhybrid.com!

 

For comparison purposes... I'm getting about 48 mpg driving cautiously (58mph)... using CC on a mostly flat commute of 50 miles round trip. I get about 45 mpg if I bump that up to 64mph. My tires are at 36psi. Temps are in the high 60's. Moderate traffic. My HCHII is a month old with 1,400 miles.

I'd say your mileage is probably normal... check tire pressure (most run 40+, and I'm headed there soon... just going up in steps to check ride harshness and noise!). As temp rises, you'll probably do better, too. CC is questionable... some say it helps, some say it hurts. Most say it's not too efficient on hills. I can't tell yet on mine. Biggest way to get MPG gains is to slow down. This car seems to love 58 mph. Unfortunately, our carpool lanes prefer 67+, so I have to make the choice... speed or efficiency!

Incidentally, with your commute of 135 miles per day X 240 business days = 32,400 miles per year. At 33mpg (your other car) you consumed 982 gallons. At 43 you consume 753 gallons. That's a savings of 229 gallons X $3.25 / gallon = $744 saved per year. Add your tax rebate to that and I'd bet you come out ahead even without slowing down!!! Enjoy!

 

Sounds like you might benefit from some of the "advanced" (but not really difficult) driving techniques to help you with the hills. Do a search for "Drive with the load" or "DWL." The long and short of it is that rather than using cruise control, you let the car slow down a little while you are climbing and let it speed up a bit while you descend. Trading kinetic energy for potential energy and vice versa reduces the overall effort required of the engine/IMA. The down side is that you can't really do it if traffic is heavy, and it does take driver input. (Then again, keeping a driver busy with driving keeps the mind off of distractions.)

My other suggestion regarding driving habits is to try it for a couple of days at 65mph instead of 71mph. At those speeds the increase in aerodynamic drag goes up sharply as velocity increases. (65mph to 71mph is in the realm of a 20% increase in the power required to maintain speed on a flat road...sounds crazy but that's how the math works out.) Even over your 70 mile one-way commute you are looking at less than five minutes difference in travel time.

As always, your results may vary. This is what works for me, and I think it could help you out if you decide to take a crack at it.

 

Instead of driving with cruise control, try driving with the load (DWL). There are several posts here at GH that mention this technique. It basically involves using the instantaneous mileage meter to maximize your mileage no matter what terrain you're driving on.

If your goal is 50MPG, try keeping the meter at 50MPG (or more) during your commute. In other words, drive according to the mileage meter . . . not the speedometer. By keeping your car at a desired MPG while cruising, you'll notice that your speed will vary depending on the terrain (slower on inclines, and faster on the downhills). It takes some practice to get the correct pedal pressure to acheive both the speed you want and the mileage reading you want, but be patient, it will eventually become natural.

Also, read Hot Georgia's article:

https://www.greenhybrid.com/learn/ar...fficiency.html

 

I have a similar situation. I drive 160 miles round trip everyday. I am mostly going up hill (more up than down) on the way to work and mostly down hill (more down than up) on the way home. I use cruise control set at 75 to go to work, where I my average mpg typically drops by 0.8 to 1.0 mpg. Although I don't have much traffic at 4:30 AM.

When I go home at 5:00 PM, there is the typical rush hour traffic. I don't use cruise as I found that the cruise constrains my down hill speed to 75 where as I can get to 80+ with very light throttle (instantaneous MPG is almost 100), although I find myself dropping down to 71 to 72 mph going up hills. There I typically pick up the 0.8 to 1.0 mpg that I lost in the morning.

Overall, you can see what I've been averaging.

You may want to try it without cruise control.

 

I'll second (or third) the comment on hills and cruise control. I live in Central PA and travel (not to work) one stretch of I-83 - which someone on this board referred to as "the concrete roller coaster". No huge hills, but constantly up and down. When I first got my HCH (February - 30's temps) I tried a few runs at that (25 miles one way) and was usually in the low 40's with CC. Without cruise I was able to bring that up to 46-47mpg in February. Now after having learned a bit more (DWL, other techniques) and the weather being milder I am typically averaging about 50mpg on that segment.

The way I would check if this would work for you is simply to look at the tach while you're climbing up hills. If you are going much over 3000 or 3500 RPM you are kicking in the less efficient cam. If this is the case you would be well advised to try it without the CC.

Eric

 

Down hill I like to travel 80+ also but I have to drop speed when I see the CHP hiding behind the billboard (the Los Angeles Police Department recruiting advertisement). The squad car on the billboard is actually a CHP waiting to catch people.


Thanks,
Shawn