Well , I ' ll try to explain but I ' ve been drinking and smoking today so try to bear with me . Let ' s assume you ' re on a normal street doing 35 mph . You have a turn coming up so you downshift rather than use the brakes . Your car is still moving at 35 mph but now your engine is at 800 rpm . When you release the pedal all of that force must go somewhere . Some transfers to the engine bringing the rpms up . Some transfers down the driveline slowing the car . The rest is absorbed by the clutch in the form of slippage of the clutch material and heat . The same thing happens during normal driving , just not to this extreme . Honestly the whole downshifting doesn ' t wear the clutch thing comes from nonsyncro ' d transmissions . Due to the lack of syncros , and having straight cut gears , these transmissions can be shifted without the clutch ever being touched . You just slide of of gear , use the gas pedal to get the rpms right , and slide into the next gear . This is horrible to due to your standard car transmission however . The lack of clutch will cause all wear to shift to the syncro ' s rapidly burning them out .