i just purchased a used Peugeot 207 verve 1.4 petrol with only 16,000 miles on clock and notice theres a smell of soot coming into the car when driving .
You haven't answered but for a start I would check the air filter and the cabin (pollen) filter. It probably still has the original ones fitted. How old is the car? When you check the oil is it black? Is it at the correct level or is the oil low? It could be overdue for an oil and oil filter change. When was it last done?