Quote:
Originally Posted by NHB
I would say that all manufactures have learned to optimize their cars for NEDC test. Every new model has an unrealistic NEDC ratings. N/A engines are no different in this sense.
What makes you think that N/A engines don't have unrealistic NEDC ratings?
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Baby turbo engines have been built from the ground up to beat the NEDC test. Now that NEDC is being replaced with RDE there's a big scramble on to increase engine capacities. NA engines might be optimised for NEDC, but the scope of what can be done is far more limited.
I have/ have had ~10 cars over the last 3-4 years. 2014 Renault Kangoo 1.6NA, 300+ kg of cargo, roof rack, 600kg of trailer, and only on the very worst traffic days would it not match NEDC, but that was only ever by 0.1-0.3L. Without the trailer it would always hit NEDC within 2km in the morning and I'd pull up on a few occasions with the SG reading 100% over NEDC. I wonder what it would have done empty and without the roof rack?
Now the Kangoo was pretty much designed from the factory to be 100% EOC ready, so that's what I did (a lot), but I rarely EOC'd with the trailer as it would cruise pretty close to BSFC. In short even with a tiny 1.6 an extra ~1000kg, extra drag from a tall trailer and an extra set of wheels, NEDC was still easy to beat.
If Renault were trying to be unrealistic with the Kangoo they were doing a very poor job of it.
My baby turbo Fiat Twinair is only driven in pretty much ideal conditions (country trips on weekends) and has yet to match NEDC. EOC and P&G don't work as there's too much enrichment when getting up to speed.
My Renault Trafic 1.6 DCi is only new, but only just hovering around NEDC being driven on the same routes as the Kangoo. It has no roof rack and is currently carrying less than the Kangoo did, but there's no way I'd be beating NEDC with the trailer in tow.
With both of these baby turbos you really have to granny drive them on acceleration (NEDC style) to get good figures, suggesting they both do very early fuel enrichment. The NA engines are more fun because you can stomp on them a bit without an economy penalty. My average speed is 26km/h for the Renaults so it's a match for the NEDC 'city' figure. 100% of people with baby turbos including BMW's 1.5 triple seem to have the same experience.