Dear Gareth and Andrew,
Thanks for raising these points, and apologies for not responding sooner.
On scrappage schemes, these are not taken into account. There is a question of whether, conceptually, they should be included. Our approach for subsidies or discounts (which is in line with practices for producing the HICP) is that the price should be measured as 'gross' if the discount is only available to a restricted group of households. This would seem to be the case for scrappage schemes, given that there are certain restrictions on age/specification of the old car. I'll reply more fully on this soon.
It is fair to say that car leasing has become more prevalent, and we are aware of this. We have previously investigated it, but we came up against a problem with finding suitable expenditure data to produce weights. This is likely to be worth revisiting.
Following the Johnson Review's recommendations, we have initiated a project to review and monitor our quality adjustment procedures. We took a paper outlining our plans to the most recent Technical and Stakeholder advisory panels, and hope to implement the outcome in January 2019.Thanks,James.