Henning (2014 VW Passat, 1.6 TDI Bluemotion)

[320touring]

Thems some good figures!

54+mpg in Edinburgh with all the usual myriad of tribulations is great for a first tank- I reckon you'll be up to circa 60 in another tank or so

[Arragonis]

Maybe. Having filled up yesterday I had the worse "going to work" average this morning at 48. The Stop-Start didn't work until I was nearly there and the RPMs were higher - I suspect a DPF regen and the "glide" MPG was down too (the DIS only shows up to 200).

Then again the A6 would struggle to break 30 some mornings, and on "DPF" days barely 25.

[cRiPpLe_rOoStEr]

I was thinking about something like this:

https://www.youtube.com/watch?v=UnkVhm3BuTY

A turbocharger developed specifically to enhance fuel savings at the same time that it improves the throttle responsiveness and low-end torque.

[Arragonis]

The issue is more torque vs. gearing than throttle response. I took Henning for a trundle through some country roads the other day and it was fine. But in 6th at anything under 80 is cruising only. Hills or lane changing means a shift to 5th or 4th. The motorway limit here is 70...

[cRiPpLe_rOoStEr]

In that video, one of the claims was that drivers could keep a longer gear in places where they would otherwise have to shift to a lower one, due to the improvement in low-end torque (which also ends up enhancing the throttle response as a bonus).

[Arragonis]

But which one uses more fuel, a quick downshift and a pulse or longer time on boost ?

[BabyDiesel]

Diesel engines usually have their max BSFC at a low rpm. I would lean towards keeping it in high gear and finessing the throttle. Of course, the only truthful answer will come through real world testing.

[Arragonis]

Yep, will do. But lay your bets....

[cRiPpLe_rOoStEr]

Originally Posted by BabyDiesel

Diesel engines usually have their max BSFC at a low rpm. I would lean towards keeping it in high gear and finessing the throttle. Of course, the only truthful answer will come through real world testing.

One of the keys to get some nice mileage figures in a Diesel is how quick they get into their optimum temperature, and to keep it constant. Some commercial drivers in my country use to go a little harder on the throttle for a while right after the start just to increase the temperature. I'd rather use a grid heater or some sort of heat exchanger to recover some ehaust heat.

[Arragonis]

Pondering a sump heater for the winter, just now the needle is moving by the time I'm at the end of my road, which is about a mile of mostly downhill coasting. Stop-Start kicks in when I stop there too.