British environmental site Clean Green Cars announced a report that says that buying a hybrid does not have significant CO₂ advantage over an equivalent diesel. The report doesn't mention other tailpipe pollutants and doesn't say that hybrids are a bad thing themselves because they do lower gasoline consumption. It's just that hybrids are more appropriate for the U. S., where diesels are virtually unknown, than in the UK. Clean Green Cars also says that we have to wait for lithium-ion and plug-in hybrids to get real benefits, since it is these two improvements that will allow more drive time on electric power alone and will increase mileage, compared to modern hybrids which can barely move on electric power alone.

Clean Green Cars came to their results by performing a test that compared three hybrids with three similar diesel cars. The six cars performed a test that involved a round trip from central London to Brighton, which involved a mix of urban, dual carriageway and motorway driving. Their recommendation: Just buy an economical conventional engine. Find the results after the jump.

Hybrids help you save gas at the pump, this is something we all know. We also know why burning less gasoline is good: fewer greenhouse gases are emitted to the atmosphere, it reduces our dependence on foreign oil and we spend less money at the pump. However, there is always the question about what is the overall impact of using a hybrid versus using a non-hybrid version. There are currently 17 hybrid models available in the U. S. market and all but one have a corresponding non-hybrid counterpart to compare with. As part of our Earth Day coverage today, we took a closer look at the following two questions:

• Question #1: How far can we drive with a hybrid powertrain compared to a non-hybrid?
• Question #2: When will the hybrid investment pay for itself through gas savings?

Before we go to the complete list let me explain the criteria we used. First of all we chose the "economy" powertrains, when we had the option. Therefore we'll be comparing mostly 4-cylinder models. In the case of SUVs, we chose the AWD/4WD versions. For a few models, we've compared them to the European diesel versions data, although this should be taken with a pinch of salt due to the EU's different driving cycles. Finally, we used $3.5/gal as the price of gasoline and added the car's MRSP price. Don't forget that some of these vehicles will qualify for various tax breaks, so you might have to recalculate our numbers for yourself. Got all that? Good, let's see the results (after the jump).

The Lexus LS600h is by far the most expensive production hybrid yet and it has just gone on sale in Europe. To date hybrids have not been as popular in Europe as the dominant diesels. AutoSpies has decided to pit the big Lexus against the established Mercedes-Benz S420 CDI and the BMW 745d. The Germans are both propelled by diesel V-8s while the Lexus uses the latest version of Toyota's hybrid synergy drive. If this test is any indication, the Germans have little to worry about for now. As expected the LS came out on top in urban fuel economy with 24mpg compared to 19.4 and 20.3 for the BMW and Mercedes. On the Autobahn, though, and cruising at 111 mph, the hybrid plummeted to 9.6 mpg while the Germans still managed 14.1 and 15.3 mpg respectively. In overall driving the Lexus also trailed. The hybrid battery pack also takes a toll on the trunk space of the Lexus. In spite of the LS600h's size, the trunk measures a mere 11.4 cu.ft while the BMW can hold 17.6 cu.ft and the Mercedes trunk measures 19.8 cu.ft.

[Source: AutoSpies]