The key points about purchasing a car which are usually put forward on this forum are:
Finance
1) If you are buying on finance, make sure the justification for buying on it finance is sound.
a) For example, if you have a car allowance and are required to have a car for business use then finance aka lease / contract / pcp is a logical business based choice. (some CA schemes require a car to be under x years old etc).
b) Finance may be the only option where the purchaser needs a car but cannot afford to by outright. However if affordability is not an issue so assuming a low rate of APR and short 3-4 year payment term is chosen this is not too much of an issue.
c) Avoid buying a car on finance that will result in a large amount of negative equity for the first couple of year of ownership in case circumstances change.
d) If you just fancy spending 200-300pm for the sake of having a new car, it is not always a good decision.
e) Look carefully between taking a PCP or Hire purchase. Obviously with PCP your payments can be lower but you never own the car unless you buy out of the agreement at the end. This is effectively the same as renting a car and does make sense if you need a car and have the mechanism to pay for it such as in point a) above (car allowance). A Hire Purchase allows you to return the car under the ‘Halves and Thirds’ rule. Effectively with the same effect as a PCP only no excess mileage charges and can work out cheaper.
Cost
2) Why spend 12k on a small basic hatch, albeit a new one, when you can spend half that on a 2 year old one with low mileage. Or get an ex demo and save a couple of K at least.
3) Why spend 12k on a small basic hatch, albeit a new one, when that budget will get some very capable cars with much higher specs and not overly upsetting running costs.
4) There is nothing wrong with buying a nice new car, it is the purchasers decision and down to their affordability and circumstances. However, the logic is often flawed where buyers are spending a lot of money to save a few hundred.
5) Smaller cars can cost very little to run in tax, servicing etc. However new small cars may require main dealer servicing for the warranty which will cost more than your local garage. Getting a free servicing deal on a new car is always a bonus
Fuel Economy
5) Small hatch diesels offer nice performance with great fuel economy, but they won’t set your world on fire.
6) When you take into account the cost of fuel, typically shorter servicing intervals and purchase costs, A diesel may not break even over the petrol counterpart until you have done 60,000-90,000+ miles. Sometimes you will never break even over buying a petrol counterpart. Example being a Volvo S60 2.0T petrol vs the D5. The 2.0T drinks fuel but second hand ones cost about 4-5k less than the D5. Another example is the Mondeo ST220, where they are considerably cheaper than the diesel version. On smaller hatches, you pay a premium for a diesel but this is often minimal over a petrol version these days. However, it all adds up.
Other Considerations
7) Everyone is an individual and has different requirements, tastes, needs etc, otherwise we would only have one brand and one type of car to choose from. Model T in black anyone??.
8) It is not so much the choice of car in most circumstances but the waste of money. The car could be a Punto, Fiesta, Mazda 2, Corsa and it really wouldn’t matter. Spending 12k on a new one, where it will depreciate 20% as you drive it off the forecourt, and probably down to 30% of its original value after 3 years is a bigger issue.