Lexus RX 400h: Problems & Solutions - READ ONLY

202 messages, Last post on Oct 25, 2006 at 6:35 AM

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What is this discussion about? Lexus RX 400h, Hybrid Cars, SUV

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#130 of 202 RX400h Cruise Control Problems by dale11 Feb 13, 2006 (2:28 pm)
My wife's 400h cruise control will vary 6-8 MPH on uneven roads. It has been back to Lexus 4 times, checked by their regional specialist. It is most prevalent when cruise is set to 55 MPH which is best speed for top MPG (about 27-29). I just got a call from Lexus headquarters in CA telling me that this is a characteristic of the vehicle and that is the way it works and they will do nothing about it. I find it pretty poor that my 2005 Prius does not have the problem and my sisters 2006 Toyota Highlander Hybrid doesn't have the problem but a $50k Lexus doesn't even have a cruise control that will work. Replies to this message: wwest (Feb 13, 2006 6:29 pm) dale11 (Feb 14, 2006 7:16 am) lexustek (Feb 14, 2006 9:22 am) wwest (Feb 14, 2006 9:53 am) kjoeb (Feb 25, 2006 8:33 pm)
#131 of 202 Re: RX400h Cruise Control Problems [dale11] by wwest Feb 13, 2006 (6:29 pm)
Replying to: dale11 (Feb 13, 2006 2:28 pm) I wouldn't surprised at all if the RX400h's cruise control is slightly biased toward fuel economy rather than exact speed maintenance.
#132 of 202 Re: RX400h Cruise Control Problems [dale11] by dale11 Feb 14, 2006 (7:16 am)
Replying to: dale11 (Feb 13, 2006 2:28 pm) Fuel economy goes down because the cruise allows the car to pick up a little speed going down the grade (this is okay, I can accept this) but when it gets to the bottom it allows the car to fall under the set speed by 4-6 MPH then it engages the electric motor and races to catch back up to the set speed and in the process runs over 3-4 MPH. Replies to this message: lexustek (Feb 14, 2006 9:22 am) wwest (Feb 14, 2006 9:53 am)
#134 of 202 Re: RX400h Cruise Control Problems [dale11] by lexustek Feb 14, 2006 (9:22 am)
Replying to: dale11 (Feb 14, 2006 7:16 am) the cruise control system when engauged can be a little jerky.the constant varaible transmission is making literally 100 decisions a sec trying to keep up with your driving requests. the noise you are hearing is the engine rpm coming up to satisfy the voltage needed to move the vehicle faster. it has been noted when cruise is used if you are in a hill terrain will decrease fuel mpg.
#135 of 202 Re: Any other info? Do you think the hybrid is smoother than the nonhybrid? [desoto1] by lexustek Feb 14, 2006 (9:25 am)
Replying to: desoto1 (Jan 01, 2006 6:30 pm) if you want more power and do more around town driving than highway then test drive a rx400h.
#136 of 202 Re: RX400h Cruise Control Problems [dale11] by wwest Feb 14, 2006 (9:53 am)
Replying to: dale11 (Feb 14, 2006 7:16 am) You mustn't forget that just because you can "see" the bottom of the downhill slope upcoming the cruise control cannot, it must want for the vehicle speed to begin to decline before it "decides" to go from regenerativge "braking" to ICE/motor torque developement. And now delay that "transition" decision just a bit in favor of fuel economy and you have a goodly level of personal frustration with cruise control.