Unknown smell of smoke

Hi there guys,

Many thanks for taking the time to at least read this.

I have a Clio on a 51 plate 1.1 Expression.

Its hard to work out or explain what the issue is here but I'll give it a go.

For the last month I have had a smell of smoke coming through the fan vent and into the car. The only way I can describe the smell is like a burnt oil smell but have no idea where this could be coming from? I stopped the car once at a supermarket and could see a faint like smoke coming from the bonnet vent in front of the driver side windscreen. When I lifted the bonnet the smoke wasn't obvious but there was a very faint cloud of smoke over the engine and it smelt like burning oil but couldn't see where it had come from. Its not always there and I can be driving along the M1 for 10 miles but it might not be obvious because the speed is blowing it away? I have checked the oil and there is plenty in. There is no increase in engine temp.

Has anybody got any suggestions as to what this might be?

Many thanks

Stewart