renault clio 1.2 dynamic billabong?

Driving along the motor way for a good 20 minutes. Car started to slightly jerk then began to loose power. Speed o metre began to decrease even though i had my foot firmly pressed on the accelerator. The car then began to slow down and would not regain any power, eventually the car came to a complete stop. Whilst this was all happening the car started smoking giving off a burning smell.
Once the car had come to a halt i tried to restart the engine but the car would just give off a powerless struggle showing that there was no sign of the engine restarting. Prior to this heating in the car has not been working, only blowing out cold air.
I started the car this morning and the engine turned over. But when turning the car off the engine gave off a sizzling noise...Any ideas what could be wrong?