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Originally Posted by SAM Hybrid
Read with interest the brief discussion of fuel economy benefits of using L instead of D. Wanted to see if someone could post information about this subject based upon the Ford event.
Thanks.
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Okay, this is something I talked to several people, including the prototype engineer about.
L, and D are the same, physically. The difference is software: when in D, you release the accelerator, you coast, when you press the brake, the regen kicks in. When in L, when you release the accelerator, they kick in the regen, same as light braking, and with some slight pressure on the accelerator you can go into a coast. Some people have been reporting better fuel economy just because of the more aggressive system that turns the engine off at 40, and that's the big difference, because in D, you have to either wait, or tap the breaks to get the engine off. You don't even get more energy back (unless your pressing too hard on the brakes and engage the friction brakes). In fact, under certain circumstances, L can be LESS efficient, because if you take your foot off the accelerator too soon, you end up capturing less energy than you spend re-accererating back to speed under certain circumstances. (Which he demonstrated as we watched the actual charge go to and from the battery)
Driving in the prototype, with all the data laptop, we drove the same course two loops around. One in D, one in L. We didn't get any more energy in L than in D.
What it boils down to is personal preference, on what you want to have happen when you take your foot off the accelerator.