I am explaining what a unibody is. Lexus has nothing to refute since Lexus is not sitting around and correcting people on the internet. People trashed the LFA transmission and Lexus did not go and correct them on the internet.
The added weight on the RCF is to achieve added stiffness. More stiffness means, better handling. So while the weight is getting added, so is the chassis dynamic capability. That is why RCF has better cornering in many turns than M4 in the chart above despite being heavier.
All of the cars these days are heavy. It is the progression of automotive engineering. About 10 years ago, 3500 lbs used to be considered very heavy. As chassis, suspension, tires get advanced, the weight goes up as well with the added safety features. I remember when E46 M3 came out in 2001, it was considered heavy at 3450 lbs because E36 M3 was 3100 lbs. The new upcoming GT500 will be over 4500 lbs. RCF is in the same weight category as the Giulia, C63 AMG, GT350, RS5. It has become the norm even for cars like Stinger or Red sport. There is nothing wrong with being 3900 - 4000 lbs as long as the chassis tuning and suspension tuning. The track edition is supposed to be stiffer and 180 lbs lighter so that puts it at a much higher performance envelope.
I came from cars that weighed 3100 - 3200 lbs. I owned a BRZ for a little while as well and it was 2800 lbs. I track my cars every so often as well, which I doubt you do. Great tossable chassis and suspension, but hated the engine, interior and performance. The RCF is infinitely more well engineered than my BRZ despite being over 1000 lbs heavier that the car shrinks around the driver when pushed hard on big sweeping turns because of how well the chassis behaves when pushed hard. I absolutely miss nothing about my BRZ other than zipping around in city traffic where my RCF feels like an overkill.
