PRIUS? ALL YOU HAVE IS BRAGGING RIGHTS...

+ Click to Enlarge BIG BUT FRUGAL: A diesel Jeep Patriot like this one almost equalled the fuel consumption of a Toyota Prius in a diesel vs. hybrid UK shoot-out.

June 12, 2008

Tests by environmental website Clean Green Cars have confirmed that current petrol/battery hybrids offer no significant CO2 advantage over an equivalent diesel of similar performance.

It's not new, but the extra information is valuable for people trying to make a rational decision about a diesel or hybrid purchase...

Way back in August, 2005 motoring.co.za reported how a Mercedes-Benz ML 320 CDI turbodiesel took on a Lexus RX 400h petrol/battery hybrid with a fuel consumption test across America from New York to San Francisco.

The ML 320 CDI (165kW) returned an average fuel consumption of 7.62 litres/100km, the hybrid SUV (155kW) averaged 8.64 litres/100km.

The test by CGC used three hybrids and three diesels in similar circumstances and the fuel consumption figures showed the diesels generally used less fuel - and therefore emitted less CO2 – than the hybrids.

Here's how it worked out (hybrids first):

Toyota Prius vs. Jeep Patriot 2.0 CRD
Toyota Prius - 7.1 litres/100km
Jeep Patriot - 7.29 litres/100km

Honda Civic vs. Ford Focus Econetic
Honda Civic IMA - 6.91 litres/100km
Ford Focus Econetic - 5.38 litres/100km

Lexus GS450h vs. BMW 535d
Lexus GS 450h - 9.96 litres/100km
BMW 535d - 9.27 litres/100km

The tests involved a return trip from central London to the south coast resort of Brighton through a mix of urban, dual-carriageway and motorway driving.

Jay Nagley, publisher of Clean Green Cars, said: "People may be surprised to learn that hybrids are no better in the real world than diesels but our tests confirmed what we had long suspected.

"Hybrid technology offers the prospect of real benefits, but only with the next generation of plug-in hybrids using more advanced lithium-ion batteries and only expected from 2010.

"Current hybrids only confer dinner-party bragging rights."

The current enthusiasm for hybrids needed to be put into context:

Hybrids, CGC says, became popular in the USA because they were the only alternative to conventional petrol engines – diesel cars are virtually unknown in the US.

Little time on batteries

With the exception of some Lexus models, which can drive at 20mph-plus on electric power, hybrids generally spend almost no time driving on battery power alone. The Prius barely gets above walking pace before the engine cuts in and the Civic uses battery power to boost performance – it generally does not drive the car alone.

Even the main advantage of hybrids – the fact that the engine does not usually idle at traffic lights – is no better than a modern diesel with stop/start technology.

"We also tested a Mini diesel with stop/start," Nagley said, "and it achieved 5.59 litres/100km. And, ironically, if the batteries run down, a hybrid will automatically start its petrol engine at traffic lights just to recharge the batteries."

No environmental benefit

Richard Bremner, editor of Clean Green Cars, added: "We are not anti-hybrid. The concept offers the prospect of genuine fuel saving with models promised from 2010 that will drive up to 40 miles on a charged battery.

However, today's models using current battery technology offer no real environmental benefit. For your next new car, we would generally recommend an economical conventional engine – for the one after that a hybrid may make sense."