Quite an old thread but I'll jump in with my figures:

I've got a year 2000 VW Passat 1.9 TDi (115bhp), and my current tank mileage figures are 59MPG (imperial, US would be 48 or so?). Official figures are 48MPG combined cycle. That seems to compare quite well with the hybrid database figures at the top of the forum.

The Passat is quite a big vehicle (5 adults + plenty of luggage), smaller diesels such as the Polo BlueMotion have a much better MPG (72MPG official versus 48MPG official, imperial).

If I had been able to afford a new Polo I would have got one of those instead - careful driving would probably lead to an MPG of around 85 - 95 (imperial). The European official figures are pessimistic, and quite easy to beat if you are doing journeys of 10 miles or more, unlike the optimistic EPA figures which can be hard to beat.

My understanding of the particulate problem with diesels is that the EPA measures particulate output per gallon, not particulate output per mile - hence high MPG vehicles are hard to get round the tests, despite possibly having a lower particulate per mile than other cars. A cynic might suggest that is to protect Detroit from efficient imports...

I used to be able to tell whether the car ahead of me was a diesel or not by the smell, but in the last decade they've improved so much I can't smell the difference any more (no black smoke any more either). I think this is a combination of ultra-high pressure injection, and low-sulphur fuel. High-sulphur fuel is terrible stuff, and I'm glad to hear that it's being phased out over there. Pity it took so long...

Costs - my second-hand Passat cost £ 2400 ($4850?), and fuel costs £ 1.06 / litre (= $ 7.70 / US gallon). A petrol car would cost me half-again in fuel. I also prefer diesels to petrol cars because they last longer - I buy them at 150,000 miles and get rid of them at 250,000 miles. My petrol cars all stopped working at around 100,000 - 130,000 miles.

I would love to see a hybrid-diesel. The MPG would be amazing :-) (100+ imperial for a Polo-sized car?)


I think the pros and cons of diesel versus hybrid are as follows: (I don't claim to be right :-) ).

* Diesels are amazing when cruising at steady motorway speeds once the engine is hot.
* Hybrids are unbeatable in stop-and-go and urban traffic
* Diesels take a long time to warm up (typically 5 miles). MPG is poor up to that point.
* Diesels take a lot of energy to start/restart the engine (equivalent to idling for 30 seconds).

-- Edit:

I found this interesting review written with a hybrid-drivers/hypermiler's viewpoint on cleanmpg of a Honda Civic with a modern diesel engine. He managed over 100MPG using hypermiler techniques (just double-dutch to me, I have no idea what he's talking about). But > 100MPG is impressive.

http://www.cleanmpg.com/forums/showthread.php?t=6526