Lexus RX 450h - invasive engine or exhaust noise in cabin

My 2012 Lexus RX 450h has developed a loud engine noise. The noise is persistent and deep - almost like a base note. I have owned a RX 450h before and it never made this noise. My local Lexus dealer cannot, or does not want to, find a solution, despite spending 4 1/2 hours removing exhaust system and manifolds. Where can I go for an expert and unbiased appraisal opinion, I don't want to return to the same dealer.

Asked on 9 July 2016 by fivelnote

Answered by Honest John
This is an Atkinson cycle engine that revs in steps rather than in a linear manner, but you know that. Unless the programming is sticking, what you describe simply should not happen. You need to find an independent Lexus hybrid specialist. If you Google <Lexus hybrid specialists> you'll find a few; hopefully one reasonably close to where you live.
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