Mercedes-Benz Forum banner

1 - 11 of 11 Posts

·
Registered
2001 ML 430
Joined
·
310 Posts
Discussion Starter #1
I have noticed that my MPG has dropped from average of 19 to about 16 now.

This started when I went from the stock 17" to 20" rim and tire package. But I did select a package that is very close to the stock dimensions as far as total diameter of the wheel. At this point I was getting about 17mpg.

I thought maybe my air filter was bad so I changed my filter and now the MPG has dropped even lower to about 16mpg. I checked to make sure it was the correct air filter and it is.

Do you guys have any idea what can cause this???
[?]
 

·
Registered
Mercedes "M32"
Joined
·
961 Posts
Eventhough your new wheels are close to original diameter I can GUARANTEE you they weigh much more than stock. When you increase rotational mass you then increase the ammount of fuel that needs to be consumed to get the vehicle up to speed. So basically what I'm trying to say is your gas mileage suffers whenever you add rotational mass.
 

·
Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
Joined
·
19,231 Posts
Holy cow! You average 19 in an ML430? You must do mostly highway driving! I only get about 15 in my ML320 around town. I do get 19 on the highway, and once got 21 driving on flat highways in Florida.

An increase in overall tire circumference would cause your speedometer and odometer to read slower than actual, which would translate into the computer calculating a lower MPG. I’d check your speed against mile markers to rule it out. The increased weight of the new rims will contribute a small drop in MPG, but it could also be your MAF going bad.

- RODNEY
 

·
Registered
1998 ML320
Joined
·
236 Posts
my ML320 averaged 23-24 MPG highway/city mix
in cold weather with same driving I was getting 17-19MPG

once it warmed up a little up here, I was getting 20-21MPG

that is according to the ML's computer thing

and, most likely your MPG dropped because of the weight of your new wheels compared to stock ... as it's been said already
 

·
Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
Joined
·
19,231 Posts
my ML320 averaged 23-24 MPG highway/city mix
in cold weather with same driving I was getting 17-19MPG
once it warmed up a little up here, I was getting 20-21MPG
that is according to the ML's computer thing
I am still amazed! I know my ML320 has some unique ECM code that could contribute to a lower MPG, but like I said, I have never gotten over 21! It is very hilly where I live and I am always in a lot of heavy traffic. I often tend to drive a bit impatiently, but even when I set the cruise below 80 on flat highway driving, I’ve never gotten close to 23! Oh, and I have checked my trip computer and it is very accurate. I just got back from lunch and it read 14.5.

- RODNEY
 

·
Registered
Joined
·
107 Posts
there is no measurement like a manual calculation ie. fuel up, reset trip odometer, drive til gas light comes, fuel up, then divide the miles by gallons used. I think this is a much better way to judge your actual mileage.
 

·
Registered
Ml 500SE
Joined
·
269 Posts
RezaR1: No doubt the tire change has thrown off your calculations. Get yourself a $100 Magellan GPS hand held unit. Set to miles, and MPH mode. It will check your speed and miles traveled very accuratly. Then do a manual calculation of your gas mileage. This is how I check the speedometer accuracy on all my vehicles. If your tires are bigger, in theory you should get better mileage because your overall gear ratio is higher (smaller number). I had an 00 430 that would get 20 MPG actual calculated at 70 to 75 steady speed on interstate roads. On the only trip I've taken in my 05 500SE I got 19.2 from Santa Maria to Fresno and back. MaybeI drive different!
Anyway, good luck!! [8D]
 

·
Registered
Joined
·
5 Posts
some ppl that didnt get their software upgraded for the trip meter etc are getting inaccurate mpg readings. Mine used to say >20, which was way too high, and now after i got it fixed, it reads a more accurate 16-17 mpg.
 
1 - 11 of 11 Posts
Top