BMW apparently considers the Mercedes SL350 as the competitor for the 640i SE and has put up a side-by-side comparison of the two cars. While the 650i is compared with the Jaguar XK
Convertible and the Mercedes SL500.
The 640i SE has a power output of 320hp and goes from 0-62mph in 5.7 secs while the 650i SE has a power output of 407 hp and goes from 0 to 62mph in just 5 seconds.
Prices (on the road) for the 640i SE is £65,680 while for the 650i SE is £73,430.