Eilers

well it is not impressive numbers, but looking back 10 years, it is about the same numbers aa any normally aspirated 3.0 liter v6 would offer.

The real difference being, that you now get almost double the power.

Twin Turbo V6 was not common back then.. It was more 4 cyl. turbo engines, known for their thirst. So I am trying to find something comparable?

Glyn M Ruck

In theory & in practice if you use the extra power it will negate the fuel saving. If you back off you can enjoy the greater efficiency as a fuel saving.

Unfortunately power is addictive.

c4004matic

The gains are amazing, that have just gone to power rather than mpg.
A simple way to think about it is to consider efficiency directly tied to engine size which is what variable displacement does. The turbo simply doesn't make an engine more efficient mpg-wise it makes it less, the air boosting simply allows it to burn more fuel. More turbos simply allows efficient boost pressure at a wider RPM range.
If you want FE from a turbo you have to keep the engine to the smallest amount of boost possible. Energy-wise the Otto-engine hasn't changed dramatically in decades, its energy conversion has hovered around 40% for a very long time. What has changed is how well we can keep it at that optimal state.
That's the reason for the move into electrical propulsion, electric motors have an efficiency of almost 100%. The downside is that we have yet to develop anywhere close to the electricity storage necessary to hold the energy equivalent of gasoline, its all in the battery!! Even with the poor energy efficiency of the gas engine, the amount of energy stored in gas is so great that no battery yet devised is close to ever competing with an internal combustion engine. You would need a battery with more than twice the energy density of the best batteries yet devised and of course it would require the ability to be replenished in 5min which is the time it takes to pump a tank of gas. Tall orders indeed. A 20 gallon tank of gas has about 700 kw of energy the best Tesla battery has 85kw. That's why despite all the Tesla advertising, its smoke and mirrors, you can't cheat thermodynamics.

Glyn M Ruck

Excellent. Someone has been doing some homework. Best post to date. However, if you don't choose to use that power it will result in fuel saving.

Fuel efficiency has improved but much can still be done. At least with turbo's you are recovering energy that would have been lost to atmosphere via the exhaust.

floridadriver

From non-engineer perspective, as conversation point and off topic a bit, I'm surprised how we're still using combustion engines. Several cars ago I thought, this will probably be my last combustion engine car. I'm a pilot, and though advances in areas, the basics of the engines of what we fly were designed in the 50's.

I understand the battery and other limitations of current design alternatives. Just would have thought somehow, somewhere, somebody smarter than me would have come up more rapidly with fresh alternatives, instead of improvements on the same mousetrap designs. We're due for a breakthrough IMO. Maybe next generation.

c4004matic

Its like nuclear fusion, its always 20yrs away.

Glyn M Ruck

These threads are crossing one another in content.

https://mbworld.org/forums/c-class-w...00-4matic.html

WCBenzDrvr

I've been averaging about 22mpg in my all around driving (mostly commute to work, plus errands here and there). This drive is half highway and half stop-and-go.

However, I drove to NYC this weekend (2 hours -- mostly highway) and got 33mpg per the trip computer. Very happy with that.

c4004matic

Very encouraging! Highway mileage should be pretty good given all the transmission features and the bountiful torque down low in the RPM range.

mda4675

I have about 6k miles on my 400 with an ave MPG of 19.1 gal. Not sure what the conversion would be. I usually keep the car in comfort, eco when I'm about to run out of gas, sport when there's snow on the roads and sport+ every once and a while when I'm feeling like I'm on the autobahn. Hope this helps

**edit** forgot to mention that I mostly city drive - about 30% highway

chicagofan00

Just under 1,200 miles in and averaging just over 19MPG with each tank of gas. My commute is about 85% city and 15% freeway though. Typically in comfort or sport with the occasional sport+ usage.

abstractls

I have about 6k miles now. I would say I average 21mpg and 70% of that is city, the rest highway. And I am known to be a bit heavy footed. When I do long highway drives thou I have actually used the Economy mode and gotten 30-31mpg.

solarflare

I recently drove 2.2k miles across to Arizona and back. The average MPG (US gallon) is around 29.79 mpg. That is about 7.9 l per 100 km. Not bad, considering the C300 only has 3.6k miles. This is mostly freeway miles with little obstacle. The city drops to about 22mpg before I started the trip. It will take a while before the engine is fully broken in.

StanNH

I believe the gist of this thread is about the C400's fuel economy. I routinely break 30 mpg on my C300, but I can't comment on the C400's economy numbers.

Glyn M Ruck

You also need the cold start open loop mixture enrichment to work it's way out of the equation. That hurts average consumption figures badly on short trips.

coladin

I am still getting 11.7L/100km in winter driving, which is impressive as mileage tends to dip in the winter.

utsenmo

my C400 has 7600km now and its trip computer fuel consumption rating increased to a steady state of 11.4L/100km (from 10.50L/100km) over the past few months of cold driving. i park my car outside all night and drive 6.8km one way to work. with 1km highway and moderate local traffic.

and i still use 19RFT performance, i'm pretty sure the loss of grip somehow increases those numbers too in toronto's snowy winter.