We seem to be getting significantly better gas mileage with my 6 speed than with my wife's automatic? & I drive the snot out of the 6 spd compared to how we drive the automatic. Might that be because her automatic still only has <1K miles on it?

I frequently start out in 2nd gear in my 6 spd....& we've been running the automatic in the W mode (starts out in 2nd).....when I'm not trying to race anyone....shouldn't they both get slightly better gas mileage starting out in 2nd?

I thought the automatic was supposed to get even better gas mileage than the 6spd????

 

I would think that starting out in 2nd. gear is actually "lugging" your engine, (making your motor work harder to get your car moving) and hurting your gas mileage. With 1 st. gear being so low, you're in it for such a short time, using it is more beneficial that just getting into a higher gear sooner.

 

Put Wilma in the "S" mode.

 

Well, there's certainly no sensation of "lugging" with either car starting out in 2nd....keep in mind these are always...mild accelerations from a stop.

Maybe Wilma just needs more miles on her or it could be the seriously cold weather we've had lately has affected the mpg, we did get over 25 mpg when we brought her back from Illinois earlier this month.

 

my bet is that it's a combination of the cold, maybe slick streets and new-ness. My auto-stick with 12K on it dleivers 22 mpg consistently so far, all winter driving, in the slop/ice and snow, and almost all commuting, so I'm in heavy traffic most of the time, speeds generally kept below 65. I'd have to guess my average speed is about 40 with the starts and stops etc. I'm thinking 22 is pretty good. It's in wintermode, won't atke that off until around April. I'm thinking she'll get about 28 in the summer.

 

My 07 XFire has only 3200 miles on it. I'm getting 20-21 mpg around town and my driving style is more 'spirited' than docile. When I drove the car back from KCMO to Upstate SC, it got around 25 mpg. And I was pushing (80-85 mph) nearly all the way to see how it handled. I've only put 1700 miles on the car since I bought it last OCT and over 900 of that was the trip back from KCMO.

The original window sticker Fuel Mileage Ratings were 21/28 with the standard 4-speed auto. So I figure the 5-speed AutoStick ought to do 10% better. That jumps the expected fuel economy to 23/31. Based on this, I'm getting about 10-15% less under similar driving conditions. Some of this is me; some of it may be optimistic fuel economy ratings. Don't have any experience with Chrysler products as I was basically a Ford owner for nearly 40 years. But my experience with Ford fuel economy ratings was close to 'real world'.

Note: I drove the car yesterday to fill up the tank (1st gas purchase in 2009!) and nearly had a 'woody' the whole time! I really love this car!

 

Chris, just because you can't sense" it, doesn't mean that it isn't happening. The simple fact is it takes more power to get the cars moving from a stationary position in a higher gear than it does in a lower gear. Your engine is simply operating more effenciently in stop and go driving using the lower gears. Try taking off from a dead stop on a 10 speed bike in a higher gear and you will feel the "sensation" I'm talking about.
Once you get the car moving, try "skip" shifting.
Lots of times I only use 1st. 2nd. 3rd. and 6th.

 

OK, I'll always start out in 1st gear & see how that goes.

Dennis, ? I don't think there ever was a 4spd auto in these cars.....just 6-manual &/or 5-auto???

 

Chris the only time I start out in second is when the streets are slick. It works much better than first. Other than that I agree with Mike that on a dry road you are putting extra stress on the drivetrain. I always try and get it in 6th as soon as I can. With the lower revs I would think that is where your fuel savings would be. My experience with manual vs. auto is that the manual always gets a little better mileage than an automatic and remember a lot of it is how you drive the car. Someone who drives agressively is obviously gonna use more gas than someone who is light on the gas pedal.
Be Safe!

 

Well, I was assuming I was getting better gas mileage when I started out in 2nd.....cause....say you start out in 1st....till 15 mph.....there's no question....that you are turning more RPMs 0-15 mph in 1st than you would if you do 0-15 in 2nd???

 

historically, the additional weight of automatic transmissions and efficiency losses through clutches resulted in automatics getting less fuel economy than manual transmissions. the crossfire with autostick weighs just 24 or so lbs more than the 6-spd and it has a lockup torque converter that eliminates the losses experienced through the clutches while at cruising speed. the autostick transmission programming should result in more efficient shift points than the average 6-spd driver which explains the higher fuel efficiency ratings of the auto. Then again it might have more to do with how the EPA tests the vehicles. Anyone ever look at the test profiles? Who drives up to 56 mph in the city, but never exceeds 60 on the highway?
http://www.fueleconomy.gov/feg/fe_test_schedules.shtml

i would guess that there would be a minimal increase in mpg by accelerating conservatively in "W" or 2nd.

 

I can't comment on the autostick (the SRT6 doesn't count), but I generally drive my roadster on the highway and get anywhere from 27-29 mpg running 70+. And there are usually short runs of up to 90-100 mixed in. I did one trip of ~150 miles at 55-60 and calculated almost 31 mpg. All this is non-winter driving.

I do accelerate gently - usually in the 2000 rpm range -- and start in first, but skip 5th. It has plenty of torque and by the time I'm going 40 mph it's just easier to slip it from 4th to 6th.

My son tends to make a lot of short, around town trips in the 2007 and gas mileage looks to be in the 18-20 mpg range. But when we picked up the car in Chicago and drove it the 170 miles back home, it got a solid 28+ mpg.

 

Do both cars have the same type tires? [summer vs all-weather.] If the stick has Conti's and the auto has Michelins that would make about a two mile per gallon difference. If that's the case you might try putting 35-36 lbs of pressure in the Michelins to get better mileage.

 

Both have all-season tires.

 

Why?

 

Summer tires stick to the road better allowing you to have more traction when cornering. Since they stick to the road so much better they take more revolutions to go, say a mile. Go to tire rack and look at the specs on an A/W tire. Then compare it to a summer tire. You will find the summer tire taking many more revolutions than the A/W tire. I think we call that "pay to play."

 

OK, as I've said before, I'm no engineer, but are you saying that two tires with equal demensions, (same hight or diameter) the stickier "summer tire" will make more revolutions than the a/w tire over a predetermined length of road?
Again, I have to ask "Why"?

 

Technically, he is correct, that according to the specs on Tire Rack, the revs per mile are not identical between the two sets of tires that came as OE for the Crossfire.

Here are the specs on the Michelin:

http://www.tirerack.com/tires/Spec.j...5YR9SPORTPS2XL

And here are the specs for the Continentals:

http://www.tirerack.com/tires/Spec.j...e%3D535WR9CW95

Each tire is 2 revolutions off from its counterpart.
The front tires are M - 829 and C - 827 while the rear tires swing the other direction M - 799 and C - 801.

These numbers mean that the tires turn XXX number of times to travel 1 mile down the road.

What causes these numbers to be different from each other, even though the sizes are the same? Simple things like the tread depth when new. Notice how both Continentals are 10/32 deep, while the front Michelin is 10/32 while the rear is 9/32.

Also, notice the difference in weight between the two sets of tires.
Running the Michelins on the Crossfire saves you ~8 lbs of unsprung, rotational weight.
I read somewhere recently that for every 2 lbs of tire/wheel weight that you drop off, its the equivalent of removing 150-200 lbs of sprung vehicle weight. I'm not 100% sure if I believe those numbers, but its something to think about.

Having to spin the heavier tires I'm sure has an effect on fuel mileage.
How drastic is that effect, I do not know.

BC.

 

My rough calculations using 25 mpg. and 800 and 802 revs per mile, the difference would be 50 tire revs. less for the bigger tire in 25 miles.
20,000 and 20,050 revs total, a difference of about .06 mpg. I think that could be ignored.
I had a brake pad that was rubbing on my wifes car, when that was repaired the mileage went up noticeably.
I have Contis on my car and I am amazed at the ease with which the car freely rolls, even just pumped up to the standard 32/33 PSI.
Then again maybe your wife drives like a bat out of hell when you are not around.

 

You are comparing two all weather tires. Of course these will be about the same amount of revolutions. Go back to Tire Rack and look at two tires that are the same size but make sure they are a summer and A/W tire. Then you will see the difference.