With approximately 560 hp and 480Nm of torque, the V10 will enable the GS-F to stand toe-to-toe with the 556 hp Cadillac CTS-V, the 518 hp Mercedes E63 AMG, and the 555 hp 2011 BMW M5.
Since all these cars pack over 500 hp, the 416 hp 5.0-liter V8 from IS-F simply won't do. Instead, Best Car is reporting the GS-F will feature a slightly modified version of the 4.8-liter V10 from the LFA supercar. With approximately 560 hp and 480Nm of torque, the V10 will enable the GS-F to stand toe-to-toe with the 556 hp Cadillac, the 518 hp E63, and the 555 hp M5.
Considering the next-generation GS will appear in 2011 (as a 2012 model), expect the GS-F to hit dealer showrooms in 2012.
[UPDATE] A Lexus Europe spokesperson has responded via their Twitter page, "Many rumours flying on Lexus GS F V10. Not going to comment on those. Only that LFA V10 is bespoke to LFA."