But, you see, the equivalent to "overclocking" a car is called "flooring it" which wastes your gas and destroys your engine. There are, ocasionally, gems such as the Porche 924S. The Porche 924 was a junk and was discontinued. The 924S was porche's attempt to bring a lower-end car back into their lineup. It used the body from the 924 which was perfectly fine but a little on the ugly side, and the same engine as their current top-of-the-line model. The 924 body weighed less and was more aerodynamic than the top of the line model and was, hence, faster and more fuel effecient. The problem is that this doesn't happen very often and cars come as complete packages and replacement parts rarely ever drop in.
In my dream world you would go to a car dealership, they would have a few cars to test drive, and then you would pick your color, seats, transmission, engine, power options, wheels etc and come and pick it up the next day. More realisticlly they bodies would already be painted with a drive train installed and that might affect your choices, but but a dealership could pop in an engine w/ transmission, seats, and change the wheels in a matter of hours if they were set up to do it. Electric options would either have to be more modular and more expensive, or tbe pre-installed on the body and affect your choice.
Currently there is no such thing as buying a car body. It comes with everything, it comes with things you may not want (In the case of the yarris I absolutely *had* to buy power windows and a bunch of other crap to get ABS, and I didn't want power windows, so I didn't buy one at all), it doesn't necessarily come in the color you want unless you want to hop through extra hoops (dealers frequently package expensive options with popular colors to get people to pay more to get the color they want, it's BS) and if you want to be at all picky you're expected to spent 2x as much or more to get what you want instead of just changing the few minor things you wanted. I could understand this for used car shopping. The car has what it has, it's had it for years. But for new cars? Absolutely ridiculus. There's a factory somewhere churning these things out, in batches, with different configurations. Churn out a batch of the configuration I want and send me one, sell the rest of them the way you ussually do to undiscerning buyers. It seems like so little to ask, but I contacted Toyota of America *directly* and they basically said "too bad, so sad". All I wanted was anti-lock breaks (the ABS had an MSRP of $300, I was expected to buy a $3000 option package to get them, the base model was $12000. Calling a dealership about a $12000 car and being emmediately asked if I wanted to buy a $24000 car instead is assanine and it happened repeatedly).
And this is why we must guard our geek haven and try to educate our peers to make intelligent PC buying decisions, or this will hapen to us next. Comparably we are in a eutopia where we can buy any part, from any vendor, made my any manufacturer, put it all together and it works without modding anything. Seriously, right now all you have to do is pair up the CPU and Mobo and everything else is completely interchangable. This is not even remotely true with cars. Even for things like headlights and seats which offer ZERO differences in functionality between one car and the next. Why are car manufacturers redesigning the damned seats and headlights for every line of cars? Because the vast majority of consumers don't make informed decisions when buying cars and don't demand quality. They don't want a new car that is "better" because they don't even know what would make it better. Next time someone tells you that they bought a new car ask them what the drag co-effecient is. Ask what the torque-to-weight ratio is. They won't have the slightest clue and they are the two biggest factors in how well the car will perform, WAY more important than HP (they will probably know that). And engine size doesn't matter at all (well, if anything smaller is better as it improves your torque-to-weight) yet it's often plastered on the outside of the car "V6 3.2L". Even real-world benchmarks like 0-60, 1/4mile, and gas mileage are largely ignored and rarely ever considered together.
Oh, about the Tesla Roadster: yeah, it's only a two seater. But it's hella fast and costs about 1cent per mile to drive it. You could convoy 4 of them for less than what it would cost to drive a typical sedan. But not only can I not afford one, they are sold out xD Tesla said they plan on coming out with some kind of family car with a smaller price tag but they wanted to make a sportscar first to raise money and get their engineers and the press excited. I'm not really in the market for a "family" car myself, so I'll probably have to pass on that one too.