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Old 06-28-2012, 02:45 PM
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voip-ninja voip-ninja is offline
Swedish Murder Machine
Location: Highlands Ranch CO
Join Date: Mar 2012
Posts: 3,898
Mein Auto: 340i x-drive
Originally Posted by Robert A View Post
How do you quantify the fuel economy bump with the 4 cylinder? The 528i when from 22 to 23 city mpg when the 240 hp 6 cyl. motor was replaced with the new turbo 4. To me, that's no improvement.
The 4 cylinder is a much lighter engine and obviously smaller displacement. It also makes use of direct injection which, as far as I know, the out-going 3.0 I6 did not offer (this is also why it makes the diesel like tick-tick-tick). The 5 series is also quite a bit larger than the 3 series so perhaps the fuel savings improvement was not as dramatic in that vehicle.

All of this is anecdotal, obviously I can't "prove" that the I6 wouldn't get comparable mileage in the F30 as compared to the N20 since obviously that combination is not coming to market... however common sense would dictate that the N20 would get noticeably better mileage, as I said, lighter weight, newer design with DI, etc.

I can say that there is plenty of anecdotal evidence in which a 2.0T with an identical setup (same car, same trans, etc) to a normally aspirated 3.0 engine (V6 not I6) got substantially worse MPG, to the tune of 25% or more difference in both city and highway mileage, as evidenced with the 2.0T A4 compared to the identically equipped 3.0 V6 A4.

Last edited by voip-ninja; 06-28-2012 at 02:48 PM.
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