Sarah is responsible for new car sales at an Audi car dealership. She must report her sales forecast to the board of directors monthly, relating to how many cars she expects Audi will sell in the next 6 months.

Historically, her predictions are 20-30% higher than the actual number of sales which are made, harming her reputation and her potential career progression.

Your job is to design a forecasting process for her. At your disposal are:

The historical sales figures for the last 3 years

The performance metrics of the sales team

Record of the sales and marketing activity

Market penetration figures

And all other facts you would expect to have access to

Please present your forecasting model in a logical way and include any self-learning elements into the forecast.