How heavy is your foot?
#4
MBWorld Fanatic!
Karo this comes from our conversation. My average is 28.1 now that I've driven reasonably. The M271 is so much more efficient than both 2.5 and 3.5 M272 engines.
#5
Trending Topics
#9
Super Moderator
#10
MBWorld Fanatic!
Join Date: Oct 2007
Location: SF Bay Area, San Diego
Posts: 1,119
Likes: 0
Received 0 Likes
on
0 Posts
C320 coupe
#11
MBWorld Fanatic!
#16
Super Moderator
![](https://staticssl.ibsrv.net/autocomm/Content/MB/mbwambassador2.gif)
Karo is "big foot". I think we are being loose with the term efficiency. For a given output of work the quadcam sixes are very efficient. Especially the 3.5l. Whereas if you make the 271 work too hard it's consumption is terrible. To achieve it's rated output WOT open loop it honks fuel for an 1800cc.
#17
MBWorld Fanatic!
Glyn is correct that if you drive the crap out of the M271 it gets poor mpg for an I4. What engine doesn't get poor consumption when it's worked hard? But in normal driving it is very efficient. Also, the 2.5 M272 is a big offender. Make it work (and by god you're gonna have to) and it is horribly inefficient by even V6 standards. I couldn't manage more than 22mpg out of it on the highway. That is a huge 10mpg difference from the 32 my M271 can pull easily on the highway. OTOH I spent a week in a 204 C350 that had no problem attaining 30mpg on the highway. I like the 2.5 V6 free-revving and refined nature but it gets poor mileage by any standards and coupled with the 7G is infuritating to drive (it's either redlining every gear or constantly shifting).
Last edited by LILBENZ230; 02-27-2010 at 08:55 AM.
#18
Super Moderator
Join Date: Dec 2006
Location: Camas, WA
Posts: 2,403
Likes: 0
Received 57 Likes
on
24 Posts
2007 C230SS; 2014 ML350 BT
Karo, that is some ugly mileage, LOL.
Last edited by johnand; 02-27-2010 at 10:04 AM.
#19
MBWorld Fanatic!
The car in question was a 07 C230 7G bought CPO at 24k miles. I really didn't care for the car at all in the multiple times I've driven it. I took your advice this last time and drove it harder. I just can't like the feel it seems to have too many gears. To each his own, though. The W203 is a great car with lots of versions appealing to lots of people. I'm glad you have found the one that fits you!
Edit:
Now that you mention it, I did spend just 80 or so miles on the highway with the 2007. The average of 22 it was giving me might have been brought down by the city driving while gettingto the freeway where it was getting about 14mpg. I don't think it's too far off though as Adidas said he averages about 22.5 overall with his 2006 6mt.
Edit:
Now that you mention it, I did spend just 80 or so miles on the highway with the 2007. The average of 22 it was giving me might have been brought down by the city driving while gettingto the freeway where it was getting about 14mpg. I don't think it's too far off though as Adidas said he averages about 22.5 overall with his 2006 6mt.
Last edited by LILBENZ230; 02-27-2010 at 10:23 AM.
#20
Out Of Control!!
Join Date: Nov 2005
Location: OC
Posts: 18,677
Likes: 0
Received 9 Likes
on
9 Posts
a quarter mile at a time
Ok, here you go. The 3.5L can be efficient on long runs but it sucks down gas (relatively) once you start using your right foot. Nothing like an AMG but definitely can be more thirsty than the supercharged 1.8. This was on a run back from Vegas. I've done better when I didn't have my wheels and going over completely flat land up between indiana and chicago, I was coming up on 500 miles on a tank of gas and HAD to stop because my bladder was about to explode.
![](https://mbworld.org/forums/attachments/c-class-w203/108266d1182906454-who-needs-prius-06-25-07_2303-medium-.jpg)
Last edited by e1000; 02-27-2010 at 11:28 AM.
#21
Super Moderator
Join Date: Dec 2006
Location: Camas, WA
Posts: 2,403
Likes: 0
Received 57 Likes
on
24 Posts
2007 C230SS; 2014 ML350 BT
The car in question was a 07 C230 7G bought CPO at 24k miles. I really didn't care for the car at all in the multiple times I've driven it. I took your advice this last time and drove it harder. I just can't like the feel it seems to have too many gears. To each his own, though. The W203 is a great car with lots of versions appealing to lots of people. I'm glad you have found the one that fits you!
Edit:
Now that you mention it, I did spend just 80 or so miles on the highway with the 2007. The average of 22 it was giving me might have been brought down by the city driving while gettingto the freeway where it was getting about 14mpg. I don't think it's too far off though as Adidas said he averages about 22.5 overall with his 2006 6mt.
Edit:
Now that you mention it, I did spend just 80 or so miles on the highway with the 2007. The average of 22 it was giving me might have been brought down by the city driving while gettingto the freeway where it was getting about 14mpg. I don't think it's too far off though as Adidas said he averages about 22.5 overall with his 2006 6mt.
I do love my car, and it is pretty close to perfect for me. Frankly, with my heavily trafficked commute, the 2.5L has more than enough power. But, if I had to do it all over again though, I would chose an 07 C350 6MT.
#23
MBWorld Fanatic!
Thread Starter
I agree with Eric, city driving with the 3.5l VS highway is a whole different story. I also agree with Glyn that these engines are pretty efficient.
If you get 20 and above in city driving then that's pretty good.
Would a supercharger or a turbo help in efficiency? I heard it does. Can anyone please confirm this?
If you get 20 and above in city driving then that's pretty good.
Would a supercharger or a turbo help in efficiency? I heard it does. Can anyone please confirm this?
#24
Super Moderator
![](https://staticssl.ibsrv.net/autocomm/Content/MB/mbwambassador2.gif)
The whole problem with gasoline spark ignited Otto cycle engines is that they suffer pumping losses at partial load/throttle. That is why Benz developed the Diesotto.
This is why a low capacity 4 will give good economy in town piddling around where a larger six will loose out. However - load the car & go on a high speed cruise & the six will win every time. Taking this argument to the extreme with a modern, efficient engine that breathes well & the ideal is to try & run a larger engine as close to stoichiometric AF ratio or leaner at constant RPM via a CVT. The 7G tries to do this. An engine like the 272 - 350 will give huge economy leaned out & running at a constant 2800 to 3000RPM - You can't really do this with the 271 without flat spots & driveability problems. It needs more fuel to achieve smooth running & high output.
This is well illustrated in the new Prius where Toyota have taken the engine size to 1800cc from 1500 to achieve better performance without giving up economy & emissions.
The Prius is, however, a dumb vehicle with all it's complexity. Diesel engines don't suffer these pumping losses at part fuel input & a little diesel Citroen will run rings around a Prius from a performance perspective while achieving 70 mpg. I'd rather have the Citroen thanks & I don't particularly like French cars.
This is also why I object to legislators trying to impose engine capacity restrictions on OEMS - rather tell them max emissions per mile or whatever will be tolerated & let the developers achieve it as they wish. I'll bet they will do this for the average family saloon with a six cylinder, approx square, petrol engine with one small turbo of 2 to 3 litres running at close to constant RPM via a CVT or 7 or 8 speed auto.
If the turbo Diesotto can be built economically then you can have the best of both worlds & possibly reduce capacity a little over a pure spark ignited engine. Further development of Atkinson cycle engines is also possible but this would require OEMs to raise capacity to achieve a specific output.
This is why a low capacity 4 will give good economy in town piddling around where a larger six will loose out. However - load the car & go on a high speed cruise & the six will win every time. Taking this argument to the extreme with a modern, efficient engine that breathes well & the ideal is to try & run a larger engine as close to stoichiometric AF ratio or leaner at constant RPM via a CVT. The 7G tries to do this. An engine like the 272 - 350 will give huge economy leaned out & running at a constant 2800 to 3000RPM - You can't really do this with the 271 without flat spots & driveability problems. It needs more fuel to achieve smooth running & high output.
This is well illustrated in the new Prius where Toyota have taken the engine size to 1800cc from 1500 to achieve better performance without giving up economy & emissions.
The Prius is, however, a dumb vehicle with all it's complexity. Diesel engines don't suffer these pumping losses at part fuel input & a little diesel Citroen will run rings around a Prius from a performance perspective while achieving 70 mpg. I'd rather have the Citroen thanks & I don't particularly like French cars.
This is also why I object to legislators trying to impose engine capacity restrictions on OEMS - rather tell them max emissions per mile or whatever will be tolerated & let the developers achieve it as they wish. I'll bet they will do this for the average family saloon with a six cylinder, approx square, petrol engine with one small turbo of 2 to 3 litres running at close to constant RPM via a CVT or 7 or 8 speed auto.
If the turbo Diesotto can be built economically then you can have the best of both worlds & possibly reduce capacity a little over a pure spark ignited engine. Further development of Atkinson cycle engines is also possible but this would require OEMs to raise capacity to achieve a specific output.
Last edited by Glyn M Ruck; 02-27-2010 at 08:21 PM.
#25
Super Moderator
![](https://staticssl.ibsrv.net/autocomm/Content/MB/mbwambassador2.gif)
Karo - the easy answer to your question is yes. The devil lies in the tuning.