What kind of speeds are you driving, and how fast are you taking off from a stop. A auto 240 needs to be babied. I wouldn't be driving more than 65, and probably closer to 55 or 60. And you can't take off in a hurry. Or you'll kill your milages as well. Also shifting too soon isn't going to help your milages either. You lug the engine down and it's not performing at it's best. Though I'm sure you're not dong this.

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