my sis and i both have the c240. both our cars make this cute purring sound. but hers is more refined and louder through out acceleration. mine purs only in the lower revs but then a growl. i have no mods, neither does she. any reason why the difference?

 

Yes

One is a Tomcat and the other is .......

 

different year, different oil change interval, etc etc

no two cars are the same even if they are the same model.

 

i do drive it more often and very aggressively.