Five-cylinder Lamborghini hinted

Lamborghini will have to give its Huracan a much smaller engine if it wants to succeed in growing Asian car markets, a senior official from parent company, Audi, has insisted.

...And Audi will have to follow suit with its just-launched R8 sister supercar as well.

Audi technical boss, Dr Ulrich Hackenberg, hinted during March's Geneva Motor Show that both the Lamborghini Huracan and the Audi R8 would have to adopt a smaller, electrically boosted engine to fulfill their potential, especially in China.

Both the Huracan and the R8 are powered by 5.2-litre, direct-injection, naturally aspirated V10 powerplants and neither of them offer an alternative, with Audi quattro boss Holger Hollerweger confirming at an R8 pre-launch event that there would not be a V8 version of the R8 in this generation.

Lamborghini President Stephan Winkelmann, on the other hand, denied the move for the Huracan, but accepted Asian tax laws made life difficult for big-engined supercars.

Until last weekend there was no obvious smaller powerplant in the Volkswagen Group that could fit the bill with enough strength and character to sit behind a Lamborghini or R8 driver.

That changed when Audi showed a TT concept car at the Worthesee festival with 441kW of power and 650Nm of torque pumping out of its five-cylinder 2.5-litre engine. And then some comments from a few months ago from everybody involved made sense.

The TT Clubsport Turbo's engine uses electrically driven turbochargers to boost the bottom end, eliminating turbo lag and inertia in a system that will be introduced on the SQ7's diesel engine within a year.

Dr Hackenberg insisted the TT concept car's electric turbo offered another 200Nm at the bottom end of the rev range and had a cracking effect on the throttle response.

Its output might have to be detuned in production if it finds its way into the Huracan and R8, but not for longevity reasons. Its issue in the concept guise is that it crunches out just 8kW less power than the naturally aspirated 5.2-litre R8 V10 motor. The concern is, especially with all that low-end torque, that it could be just embarrassing at the lights for the atmo car.

And, at 2.5-litres, it would cut cleanly through China's tax laws that begin to bite at 2.0 litres, but bite hardest above 4.0 litres.

"We need alternatives especially for the coming markets," Dr Hackenberg said in Geneva.

"The tax is too high in many Asian countries. They need to offer a smaller engine in R8 and in the Huracan to succeed there.

"For some countries, it's necessary to have smaller engines."

China is the most prominent of the countries Dr Hackenberg referred to. Since March 2013, China has levied an annual consumption tax on cars, rising with engine capacities. Upwards of 2.0 litres, the tax jumps to nine per cent and continues on a sliding, linear scale, to 40 per cent for engine capacities of 4.0 litres and above. There are no distinctions between turbo and non-turbo motors.

That alone would make it pointless for the Huracan and the R8 to use a variant of the biturbo 4.0-litre V8 from the RS6 and RS7, because it would attract roughly the same per centage of consumption tax as the existing V10s.

But the question had always been which smaller engine could work in a Lamborghini? While Winkelmann doesn't want to even be drawn into the conversation, Dr Hackenberg isn't so reticent, suggesting three litres would be an acceptable compromise.

But, he said, it could only be true to the brand if it did not run a normal turbocharger.

"Lamborghini they have an upper position and that's to only have a naturally aspirated engine. It's something very special," he said.

"The response is better than the turbocharged engines and the response is the key to the character of a Lamborghini."

Response, yes, but not the outright speed, the noise and the dramatic fury expected of an R8, much less a Lamborghini.

"We might use a turbocharger in a less-performing version of the R8," quattro GmbH boss Heinz Peter Hollerweger suggested at a pre-launch event for the R8. "We might have to."

The issue the new concept five-cylinder engine creates is how to guarantee the smaller-engined car would actually be the lesser performing model. This is also a reason why quattro has ruled out using the family's 4.0-litre biturbo V8, which topples the power and torque figures from the base R8 V10 with 412kW and 700Nm.

Hollerweger has already implied that any smaller-engined R8 or Huracan would retain the non-turbo throttle response by directly boosting the engine with an electric motor. That would dictate 48-Volt fast charging and discharging technologies and a lithium-ion battery pack to generate enough energy to help the internal-combustion motor.

"Electric boosting would be necessary for any smaller motor, even if it's turbocharged," Hollerweger admitted.

"Electric boosting will be necessary to reduce CO2 for us. We can use it for lowering emissions and we can get a lot now from boosting," he said.

"Naturally aspirated engines are a niche technology now and if you don't want to have a turbocharger there is only one way to do it [boost and go faster]. That's electric.

"That means electric battery and electric motors in the transmission with a fast battery to discharge."

The development that will make electric boosting viable for production supercars – even those with smaller capacity internal-combustion engines – is surprisingly well advanced, he admitted.

"In the future of batteries there will be two different chemistries in the development ways. One will be for the fastest discharge use and one will be for low-distance, day-to-day driving and obviously we will look to the fast-discharge research.

"The batteries are being developed so much faster now that the car makers are involved. I thought it would be consumer technology that drove it but it's the car industry."

But using electric motors to give a leg-up to smaller internal combustion engines comes at a price – both in cost and in weight, which is the traditional enemy of supercars.

"The problem with electric boosting is that this type of battery has to be much heavier and the weight disadvantage of the battery has to be countered by the performance gain," Hollerweger admitted.

"This is where we are developing a lot. If you want to boost very often then you need a big battery and that means a lot of weight."

But there's another issue for any smaller-engined Huracan or R8. At this month's RS3 launch, Quattro GmbH engineering boss, Stephan Reil, categorically stated there was no approved development project to slip a lesser motor in the flagship sports car.

"There are a lot of questions unrelated to the engineering that have to be answered before we start with the engineering," he said.

"There are questions of the stability of the tax laws, questions of how much additional volume it would give us, questions of timing, questions of complexity and questions of whether people in those countries even want us to do it," he said.

"And, yes, there are questions of the integrity of the badges. If we could do something that added something to those badges without taking anything away except cost and emissions, and if there was a market, then that's when we would start engineering a car like that.

"But we haven't yet. But it has been spoken about."