Hi,
I have had my Lexus IS250 SE-L for 2 months now and have noticed that on my commute to work, whilst travelling uphill at a steady 30mph in 5th that the revs sit around 1100 to 1200 then all of a sudden the engine noise changes, as if its dropped down to 4th but it is still in 5th, and the revs shoot up to 1800 without any significant increase in speed. Then after a couple of hundred yards, the engine noise drops again and the revs drop back down to 1100, this then repeats all the way up the hill.
Anyone any ideas why?
if it dropped down to 4th because we are going up hill slow and steady I could understand it but it stays in 5th!
Cheers