OK, so it's not hybrid news, or even related to the US - but interesting none the less...

Making a monkey of the diesel myth

 

Hi Stoner:

___Thanks for the link … I have to assume that smallish 1.0 L SI-ICE is a poor performer? Have you been following the Can someone educate me on hybrid cars compare to diesel engine cars??? thread?

___Good Luck

___Wayne R. Gerdes

 

Anyone have any idea how much those 2 cars weigh?Weight alway counts even in hy driving since you always have to slow down speed up.I assume the Diesel is 50-100 lbs heavier.
What is the hp output for those 2?No reason a 1 lt ICE couldn't make 75-80 rwhp pretty easily.
The diesels have a theoretical advantage because of the compression-lack of throttle plate and they can burn extremely lean, but a small ICE with fairly big bores-shortish stroke-fewer cyl can narrow it.
The small 3 cyl will have less ring-cyl contact area per RPM and per hp produced.It will also have less area exposed to hot combustion gases,so less energy lost that way. If it is small enough it will have its throttle plate pretty far open negating the Diesels advantage of no plate.
I'm not too surprised about this. In the mid 80's we had several carbed car that would get 40+ mpg at 70+ mph.Not FI not electonic controls-no O2 sensors-no knock sensors- no 4 valve head-nothing to max out efficiency.Small cars(2200 lbs)-small,but decent- motors.This describes our 1985 Corolla.Thanks.Charlie PS-no airbags,no abs-lotta good things that add weight,but it might have had an iron block also.

 

Yes I've been watching that thread - a bit of a contradiction to what Clett said about diesel varients out performing petrol models (sorry Clett!).

I wouldn't say it's that much of a poor performer, it's comparative to other EU Superminis (even though I would class the C1 as a mini-supermini) and is 2 seconds quicker to 60 than the diesel (ahem) - fine for the grandparents, the teenage daughter and mum (when dad has taken the 'other car' to work)

The same unit is going into a version of the new EU Toyota Yaris, as well as it's sister cars the Aygo & Peugeot 106.

 

Oops!

I answered the "educate" thread first, looks like it would have been much better here! Anyway, here's what I wrote there:

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I have seen the Times report before and I was very surprised when I read it!

However when I looked more closely I saw that they only went 116 miles before stopping for fuel again. As this amounts to only about 6 litres of fuel, I doubt very much they were able to accurately fill the tanks to exactly where they were when they first stopped.

This was found to be a major problem at the recent Tour de Sol, where the fuel computers of a lot of hybrid owners produced mpg figures greater than 100, yet when the organisers did the calculations by adding fuel to the tank they found it very difficult to put in the same amount of fuel and their figures were way out, often by as much as 20%. The problem was worst for the gasoline entrants due to the charcoal evaporation cannister. The organizers are considering switching to going by the onboard computers for next year's event for this reason.

So I'm not convinced that the Times test is representative of what diesel owners really achieve!

Over here we are fortunate to have many vehicles that have both a diesel and a gasoline variant in the same body style, so it's relatively easy to compare mpgs between the two. A useful resource for those wishing to see some technical data on what we have available in the UK is available here: http://www.parkers.co.uk/choosing/specs/

Some examples from these tables of vehicles with equivalent power outputs:

[Make, model] -- [gasoline mpg] -- [diesel mpg] -- [improvement]

Audi A4 ----------- 36 --- 51 --- 42 %
BMW 5-series ------ 31 --- 47 --- 52 %
Ford Fiesta ------- 47 --- 64 --- 36 %
Honda Accord ------ 38 --- 52 --- 37 %
Freelander -------- 27 --- 37 --- 37 %
Merc C-class ------ 38 --- 47 --- 24 %
Peugeot 206 ------- 45 --- 65 --- 44 %
Skoda Fabia ------- 47 --- 61 --- 30 %
Toyota Yaris ------ 50 --- 64 --- 28 %
Vauxhall Vectra --- 38 --- 49 --- 29 %
VW Golf ----------- 40 --- 53 --- 33 %

These are all for manual transmission and the average improvement is 36% over gasoline. Having owned both gasoline and diesel vehicles I would tend to agree with this being a reasonably accurate rule of thumb.

 

Clett, what that table does not show is the horsepower for the gasoline versus diesel versions. In most cases, you have to give up power in order to get the diesel version of a vehicle. Thus, it's not just a pure gain in fuel economy; you lose power to gain fuel economy. As such, in theory you could just use a smaller gasoline engine that has less power to improve fuel economy, so it's not really apples to apples most of the time.

 

Hi AZCivic, I tried to make the comparisons by choosing from the lists the vehicles most evenly matched for power. Occasionally the diesel is the more powerful, but usually they are within +/- 10 hp.

By the way everyone, those figures are all in UK gallons!