High end car manufacturers do not dynamically adjust list price to take into account currency fluctuations. The car is designed and built to be sold at a certain pricepoint - Land Rover are not going to reduce the list price of a Range Rover by 10k Euro. They are going to keep the price more or less where it is - inline with the price of the competition - and the benefit will be taken by the manufacturer and not the consumer and therefore doesn't translate through to inflated demand. The price in each market has already been calculated and set at the point at which supply and demand meet best - it's already been decided that if the Range Rover cost more, they'd lose too many sales, and if it cost less, they'd needlessly be giving away margin. That's why it's the price it is in every market it's sold at. Products like this are not sold using 'Cost Plus' pricing strategies.
Currency movements are not 'supply and demand 101' - they are more complex than that and have more effect than simply reducing price and thus increasing supply (or vice versa).
Which is a good thing for our domestic manufacturer's Indian parent company, but it isn't going to suddenly massively increase demand for the products. There is simply no need to price a Range Rover at 10k less than it's equivalent competing product so it doesn't happen.
So, clearly I'm not going to sit here and argue that a weaker sterling has zero effect on exporters. Clearly it does - for exporters who export low margin high volume products which are typically price elastic they are able to sell more competitively, but we don't do much of that. For exporters who export higher technology, higher quality or more specialist products they are able to increase their margins.
However the point is that these benefits are generally outweighed by the negative effect the incredibly weak currency has on the cost of items we import - it increases the price of raw materials, which increases everyone's costs and ultimately drives up the price of even domestically produced items. It increases the price of finished goods we buy from abroad - so your cars, your washing machines, fruit, etc etc all goes up in price (or the retailers suffer lower margins, which has destructive long term effects).
You constantly labour under the misapprehension that we are like China - a manufacturing powerhouse putting out millions and millions and millions of disparate low cost low margin products every day and shipping them across the world. For an economy like this a weak currency is beneficial because the products they sell are price elastic and the less the currency is worth, the cheaper they can sell volume items for.