At 270bhp, this is the most powerful Exige Lotus has ever built yet it is also one of the most environmentally friendly. The Exige 270E Tri-Fuel, to give it its full title, has been produced by research engineers at Lotus Engineering to demonstrate how straightforward it can be to develop high performance carbon neutral vehicles using sustainable liquid fuel.
The 270E can run on either petrol, ethanol or methanol or a blend of all three if necessary. It forms part of a research program looking into the technicalities associated with burning mixtures of petrol and alcohol fuels and since the Exige is already supercharged, also dovetails neatly with the trend towards downsizing by using smaller capacity boosted engines to improve efficiency.
A green Lotus Exige? How can that be any fun?
Oh, it’s fun. On Lotus’s southern test track the Exige quickly demonstrated just how potent it is. Cruising at low throttle openings the engine sounds quite innocuous, although because it’s close-by behind the seats a few unfamiliar noises like the clicking of injectors circulate freely around the cabin.
But squeeze the throttle hard and the Toyota-Yamaha engine swiftly delivers a fierce punch in the back, the buzz of the supercharger increasing in volume along with a rush of intake air as the Exige pelts towards the horizon at a blistering rate.
It’s proper race car stuff. Short-shift gear stick, six closely-spaced gear ratios, hugely powerful AP Racing brakes, a steering wheel kicking gently in the hands and lots of noise. The Exige’s huge grip and near perfect balance complete an intoxicating package.
Tell me about this green engine
The 270E is based on the supercharged Exige S which normally puts out 220bhp, or 240bhp with the performance pack. Because the alcohol fuel has a higher octane rating than petrol, the 270E ignition timing can be advanced sooner without the risk of detonation despite the relatively high compression ration of 11.5:1. So select a high gear, drop the revs to 2,000rpm, floor the throttle and the 270E will pull smoothly to the red line without a fuss.
The Tri-Fuel also has two extra injectors mounted up-stream of the supercharger which kick-in at around 80 percent of full power and load. The cooling effect of the alcohol makes the intake air more dense resulting in higher power. That means 270bhp @ 8000rpm while maximum torque is up from 158.6lb ft @ 5500rpm to 184lb ft.
Where is Lotus going with this?
The Lotus position is simple. Following the excitement about hydrogen powered cars over the last ten years, it takes the view that although the end game for sustainable fuel is still hydrogen, distributing that hydrogen to point of sale is neither practical nor efficient in energy terms.
So instead Lotus still wants a move to a hydrogen economy, but then the idea is to turn that hydrogen into methanol by combining it with CO2 washed from the atmosphere. Then put that into a conventional fuel tank using a conventional engine as we do now.
It’s a much quicker path to sustainability than fuel cells. Lotus could have the technology on the market in five years but it could take 15-20 years to make methanol a familiar commodity on the streets.
What about value for money?
Alcohol fuels do contain less energy than petrol so you need more to travel the same distance. But Jamie Turner, Lotus chief engineer, powertrain research, thinks the government should start selling and taxing fuels based on energy content rather than volume. Think, ‘how much energy have put in my car,’ rather than, ‘how many gallons.’
Turner also reckons that in production volumes the additional manufacturing cost could be as little as £40 per car.
Isn’t methanol poisonous?
Yes. But additives will make anyone daft enough to drink it bring it up again and petrol and diesel are equally poisonous. Additives can also make methanol burn with a visible flame. In its pure form, methanol burns invisibly, something firefighters are worried about. It’s also corrosive and cars need appropriate fuel lines and seals to handle it.
Verdict
There’s no doubting the Exige Tri-Fuel’s credentials when it comes to performance. But where it really excels is in demonstrating that a car which can be CO2 neutral at the tailpipe (when running on pure alcohol) can be as exciting as ever.
Methanol was widely touted by big guns Daimler-Chrysler (as was) 10 years ago. Later, attention switched to finding ways of carrying hydrogen on-board the car. History may one day show this to have been a mistake.