Here’s a bit of relevant information from the world of business.
At a given point in time you are trying to decide whether or not to spend money on a project. The money you have spent up to that point is called ‘sunk costs’ and all too often people argue that they have to keep spending because they can’t “throw away all that money we invested”. It’s a mistake. If you look through the rules on project financing they will all say the same thing: you ignore what has been already spent and you look at what you need to spend now and what return you will get on that investment.
If spending £300 will get you a year of enjoyable driving then that seems like a reasonable return on your investment.
As a current example - I own a 2006 BMW 530d M Sport Touring Auto. Lovely car, but it’s getting a bit long in the tooth and at the beginning of the year I decided that it was time to replace it. So I sat down and worked out what I would need to invest to change it to a newer car of comparable specification. The answer, after a bit of careful working out, was £3-4k. I looked at the return on investment I would get on spending that £3-4k and the answer was a car that does the same but might cost me less in repairs and maintenance. But even if the current car were to cost me £1k a year in repairs and maintenance more than the new car I could continue to run it for 3-4 years for the same money I would spend on replacing it.
I decided to keep the car and earlier this week it went in for it’s MoT and service. Total cost just over £400, and that included a new battery. So instead of spending £3-4k I have my nice car for the next year for the meagre outlay of £400. The money that was left from the £4k budget was used to buy my new NC1 so serious result from my perspective! I now have two nice cars!