In the last week I have been lucky enough to see in close-up detail two unique cars, both of which are made largely from scratch.

The Skelta, an out-and-out racing car that also happens to be road registrable, uses a largely untouched Honda S2000 engine – complete with factory management – and driveline. The frame comprises small diameter chrome moly round tubing mixed with boxed carbon fibre sections, while the suspension is fabricated from first principles.

The Bullet started life as a Mazda MX5 (Miata) into which a Lexus V8 was shoe-horned. However, the cars now run few Mazda parts, instead being built up on a frame comprising largely rectangular and square tubing, with suspension arms sourced from other cars (or built from scratch, depending on the specs). However, the basic underfloor – or ‘tub’, as the company calls it – is still Mazda, as are the doors and some other bits and pieces.

Both the Skelta and the Bullet are ludicrously expensive for what you get; and both manufactures I believe make little or no profit in selling the cars.

The trouble is of course that mass production makes normal cars incredibly cheap. Conversely, if you’re building by hand what are effectively almost one-offs, the costs are huge. It’s not hard to walk around either car totting-up totals for the frame jigs, the frame, the brakes, the suspension, the body moulds, the body panels, compliancing and so on. The dollars add up scarily quickly. And if the companies had designed and built their own engines, the costs would be so high people would just laugh loudly and walk away.

But in the wrecking and used car yards of the nation, cars have simply never been cheaper. And their technology has never been better. Attributes once seen as the province of only exotic cars – like double wishbone suspension front and rear, big disc brakes and all-alloy engines making a lot of power per litre – are now common. And cheap.

So here’s what I don’t understand. Rather than take just some bits from a donor car (whether that’s a Honda S2000 or a Mazda MX5), why not build the one-off car around all the mechanical bits of another car? The engine, driveline, brakes, suspension, instruments, wiring loom, engine management, traction control, ABS – the lot! In the same way as the Skelta, you’d then use a custom lightweight tubular frame to tie all the bits together, using the original locations of the suspension pick-up points and engine and driveline mounts. You’d then dress it in a minimalist Clubman-style body. Over the original donor car you could lose the rear seats, the dashboard, the sound proofing, most of the panels, the heater, the air conditioner – pretty well everything but the basic mechanical package.

If you picked a car with a low-mounted engine (like an Impreza WRX) or a mid-mount engine (like a Toyota MR2) you could surely change the shape of the body very considerably so that it wouldn’t resemble the donor in any visual way. And with a lightweight spaceframe and without the luxuries, how much weight could you lose? Thirty per cent minimum?

You’d have a unique looking car with an immediate 30 per cent power/weight ratio improvement, still with factory mechanical reliability and spare parts availability. Clearly, with a turbo engine, that 30 per cent could very easily become far more if you wished. And, over the Skelta or Bullet, surely costs would be at least halved. No, you probably wouldn’t have the handling or brakes of the Skelta or the gut-wrenching bottom-end torque of the V8 Bullet, but you may well have AUD$50,000 more left in your pocket while still gaining something that could be a lot of fun.

Look, I haven’t done the sums in detail, but I would have thought that a spaceframe chassis could easily be designed, engineer-approved and built for AUD$20,000. A complete donor car would cost a similar amount (or much less if it had been rolled!) which leaves $10,000 for putting it all together and providing some body panels. Remember, you could even take the seats from the donor car, not to mention the fuel pump, the driveshafts, the door locks, the interior door handles, and so on. That’s with a total budget of AUD$50,000, well under the price of the two cars I have been discussing.

It’s my opinion that both the Skelta and the Bullet won’t be long-term commercial successes. I admire the purity that both companies are bringing to the market and the lack of compromise that this entails. But re-inventing the wheel when cars are already so good and so cheap is not a commercially viable option.

But I think that taking all the good bits from an existing car and then mixing them with a custom frame and simple bodywork might be…