Having had 4 x GS 300, time for change, myself and my son bought IS 220d each on the same day, both blue, his black wheels, mine silver. After 2 weeks he was bored of the lack of power, stating "this is an old man's car". I told him to sort it, he did. Found a company that specialises in "tweeks and problems solved". They came to our house, 30 minutes later, his is diving like a new car, I tried his car, had mine done mine the same. No turbo lag, no fade in the gears, no lack of power and over the last 2 weeks fuel up 8mpg.
This feels a different car. This is what a Lexus should be.
My other son had his BMW X5, 4.4 petrol done at the same time. Saves another 11mpg for him. 3 cars £650. Money well spent.