MPG difference btween M135i and 135is

I am surprised by the large difference in BMW-reported MPGs of M135i hatchback (Euromarket) and 135is (US market) respectively: 38mpg vs 28mpg
Both cars have the same engine (turbo 320hp) tuned slightly differently: (332 pd for M135i vs 317pd for 135is). M135i slightly lighter: 3307pd vs 3373for 135is.
Can someone explain the large difference in MPGs? Thanks in advance.

Originally Posted by Eldee

I am surprised by the large difference in BMW-reported MPGs of M135i hatchback (Euromarket) and 135is (US market) respectively: 38mpg vs 28mpg
Both cars have the same engine (turbo 320hp) tuned slightly differently: (332 pd for M135i vs 317pd for 135is). M135i slightly lighter: 3307pd vs 3373for 135is.
Can someone explain the large difference in MPGs? Thanks in advance.

3 major things:

Different mpg measurements - 38mpg is the rating in real (imperial) gallons, equivalent to 31.6 US mpg;
8 speed automatic transmission is more efficient than the 7 speed DCT and 6 speed manual;
Efficient dynamics with auto start/stop and an alternator that tries to charge mainly while the car is decelerating.

Thx for Reply.
If you compare the numbers for the Coupe 135i btween BMW US and BMW UK you still see large difference of almost exact same car (135i is coined as 135i M in UK)
Hp: 300(US) vs 306(UK)
Torque: 300(US) vs 332(UK)
Weight: Same at 3373pd
Both 6MT
MPG city: 20(US) vs 19(UK)
MPG HWY: 28(US) vs 37(UK)
For the life of me I cannot understand this huge diff in MPG hwy.
ETA of my 135is (6MT, grey metalic) is in 2 weeks. I'll definitely post some numbers regarding this intriguing values....
Cheers

MPG I reported are in us gallons. no fault there...

This is what BMW website reports for MPGs for coupe 135i
UK:
Consumption
Urban (ltr/100km): 12.1 [11.7]
Urban (mpg): 23.3 [24.1]

Extra-urban (ltr/100km): 6.4 [6.7]
Extra-urban (mpg): 44.1 [42.2]

%%%%%%%5
US:
Manual transmission – City/Highway : 20/28 mpg

deleted.

The two tests aren't comparable. The driving cycles are different and the USA EPA multiplies by a correction to lower it from what their test observes. You can't even compare new EPA mileage numbers with those from ten years ago since the test changed to lower the numbers closer to real world results.

To see this illustrated, find a car that the EXACT same between what's sold in the USA and what's sold in Europe. I picked a new F30 328i manual.

Originally Posted by BMW UK site

Consumption
Urban (ltr/100km) 8.1 (29.0 mpg US)
Extra-urban (ltr/100km) 5.1 (46.1 mpg US)
Combined (ltr/100km) 6.4 (36.8 mpg US)

Originally Posted by BMW USA website

City: 23mpg
Highway: 34mpg.

Thx CWSQQBM,
Your reply makes sense to me.
I'll post real time numbers after I drive the vehicle.
Cheers.

I've had my 2009 135 vert 7spd DCT for 3 months now, put on about 5000 miles so far (daily driver and a couple road trips). I'm getting 22.8 mpg real world average. Up to 27 on one road trip. Forget the EPA, you didn't buy an economy car. Just enjoy those 300 + horses!!

I average nothing in a normal 135i. Even my gf averages 17mpg. Use the throttle people! Lol

Wow, your gf must really have a lead foot. This afternoon I took an epic, tire melting, red-line tapping, full throttle romp through the mountains of NC and still got 21.4 mpg! I'd have to take the gas cap off so some could slosh out to get 17.

Originally Posted by Eldee

Thx for Reply.
If you compare the numbers for the Coupe 135i btween BMW US and BMW UK you still see large difference of almost exact same car (135i is coined as 135i M in UK)
Hp: 300(US) vs 306(UK)
Torque: 300(US) vs 332(UK)
Weight: Same at 3373pd
Both 6MT
MPG city: 20(US) vs 19(UK)
MPG HWY: 28(US) vs 37(UK)
For the life of me I cannot understand this huge diff in MPG hwy.
ETA of my 135is (6MT, grey metalic) is in 2 weeks. I'll definitely post some numbers regarding this intriguing values....
Cheers

That is quite interesting in light of 6MT and UK to UK numbers. They're different generations though (135is is old e82 and the M135i is the new F20 platform). But still same engine and probably very similar manual trans. Haven't compared the weights yet ,but is the F20 lighter? Only other guess would be start/stop as somone else menteiond (and that doesn't explain highway numebrs). I suppose better aerodynamics help too. My guess is that when the US finally gets the F20 (in coupe form) the EPA numbers between the old and new won't be quite as different.

The F20 is slightly lighter than the E82 (ca 30kg: F20 has new chassis). Aerodynamics are similar. Engine is same. i think the diff in mpgs is due to diff ways for evaluating btwn US and UK

The 335is with a JB4 does right around 22 inside Raleigh City limits. I expect the 135is will be pretty close.

Got my 135is 6MT yesterday (almost 3months waiting time). A blast! About MPG: combined (with HWY NMT 60mph): 33mpg!!! combined (with HWY NMT 80mph): 29mpg!!!
Drove in 6th whenever possible, few nice rev ups at green lites... oh yeah and the engine sound: a marvel!!!

BTW I am selling the orginal rims/wheels (never used, changed at dealer b4 pick up)
Double Spoke (Style 313M) light alloy wheels, 18 x 7.5 front, 18 x 8.5 rear; 215/40 front, 245/35 rear run-flat performance tires (Tire: Bridgestone)
Value $4000. Sold $2000