Why does a Porsche cost so much for such low horsepower comparing to other German makes?

I don't know the history of Porsche that well,but a Cayman with 300HP or so cost as much as a BMW M3 with 414HP.

Is it the history of the company that makes it expensive or the material? Resell value?

In short, because cars are not sold on a dollar/horsepower basis. There are a wide variety of factors that figure into any car's price point, for a performance car, how well it performs will be a major factor... but again, horsepower is a measure of one characteristic that affects performance, it is not a measure of performance.

Consider the following cars, all near the same price point:
Porsche Cayman S = ~$200/hp
BMW M3 = $160/hp
Cheverolet Corvette Z06 = ~$140/hp
Lotus Exige S240 = ~$275/hp
Radical SR4 = ~$360/hp

Now... in terms of pure performance, which do you think is the fastest? Yes, it's the ringer of the bunch. The Radical would completely destroy any of the above dispite having less than half the horsepower of the BMW. The Exige, the Corvette, and the Cayman will also all enjoy an advantage over the heavier BMW around a track - the BMW is about 700 pounds heavier than the Porsche... and more than 1700 pounds heavier than the Lotus... and more than a ton heavier than the Radical; in short, it needs the extra power just to keep up!

But just as horsepower/dollar isn't the only criteria of a car, most will not go strictly by performance/dollar. Which is why you would most likely not even consider the Radical (aside from it not being street legal in most countries). The BMW is the only car I mention here with a back seat. And while the spartan Lotus could make any car look luxurious, the BMW still looks good against most other cars in this department.

And while the Corvette offers ALOT for the money, it will unfortunately never match the build quality of the Porsche or the BMW, even though it will offer more performance/dollar.

So the end result of all of this? When all is considered, the cars all offer a different set of strengths for their price... which of those strengths mean the most will help determine which makes the most sense for you. But if it's strictly horsepower/dollar, you will probably want to look to someplace other than Germany, and if it's strictly performance/dollar, again, not so good (though in the last one, the Cayman will more than stack up against the more powerful BMW).

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