[StanDiego]

Originally Posted by Horseman

Having had the 30i for over 2 years, I'm telling you that the quickness of the M40i was NOT the reason why I wanted to upgrade. Though it's a nice benefit...

I wanted it for more superficial reasons. The sound of the exhaust. The peace of mind that I have knowing I have the highest trim. Not having to explain to other car enthusiasts that I "just have the 4 cylinder."

I applaud your honesty.

[Westside Guy]

Originally Posted by StanDiego

I applaud your honesty.

The difference between men and boys is the price of their toys!

[BEAR-AvHistory]

I hear thing twisty road thing a lot. Interesting but would expect I can cover a Carolina Moonshine 2 lane blacktop a lot quicker in a M4.0 than in a 3.0. I have/do out run my old 917 Boxster S over these roads so am pretty sure the 4.0 is very well adapted for running country roads.

Not saying the 3.0 over a twisty is not fun but am saying why is it implied M4.0 is less fun?

They don't put less power in road course cars to make them quicker.

Top Nurburgring stock street cars all have a lot of power including the fastest street legal 4 door sedan a 2023 550BHP M3CS @ 7:23.975.

Makes a Porsche sandwich Porsche 911 Carrera GTS (7:23.77) - BMW M3 CS (7:23.97), Porsche 911 GT2 RS (7:24.00)

[StanDiego]

Originally Posted by BEAR-AvHistory

Not saying the 3.0 over a twisty is not fun but am saying why is it implied M4.0 is less fun?

I'm sorry I missed it. Who implied that? It's obviously not true.

[SpeedyATL]

Originally Posted by MisanoblueZ4

Also just a note.

C&D recently did an updated review of the M40i and clocked the fastest time yet of any publication (US version)

0-60 3.5s
1/4 mile 12.0 @ 116mph

75mph mpg’s 37

The Z4 M40i is a seriously quick sports car if you want that, I doubt the general public would have any idea they can scoot that quickly.

Well, they used a number with a 1 foot roll out, so thats why its the quickest we've seen.

When it comes to hp, i think we all might be forgetting that 382 is far from the right number. Although it does vary, dinan dyno'd the b58 and they got some impressive numbers. Of course some of this depends on the conversion factor used. But they have little interest in over estimating the stock numbers.

Also makes for an interesting comparison to the 4 cylinder (B46) similarly estimated. Dinan shows a 'converted' difference of 172hp at the crank.

[Horseman]

Ok.. for the M40i ... are those charts saying that it has upwards of 468 - 509 hp? Maybe I just don't know how to read these.

[ebirotedu]

With the Dinan mods the graph shows 468 crank HP and 509 lb-ft of torque.

Dinan is using a 17% drivetrain loss correction factor to come up with that number looks like.

Without the mods they’re estimating 448hp and 450lb-ft torque at the crank.

Originally Posted by Horseman

Ok.. for the M40i ... are those charts saying that it has upwards of 468 - 509 hp? Maybe I just don't know how to read these.

[MisanoblueZ4]

Originally Posted by ebirotedu

With the Dinan mods the graph shows 468 crank HP and 509 lb-ft of torque.

Dinan is using a 17% drivetrain loss correction factor to come up with that number looks like.

Without the mods they’re estimating 448hp and 450lb-ft torque at the crank.

Trap speeds of 116mph in the 1/4 is certainly showing well over 400hp crank. Nearly 450ish is believable, this is a 3500lb car with less tire then a C7 Corvette and the Trap speeds are not far off.


Here is a 2017 Grand Sport test by C&D, 3.9 0-60 12.3@116 quarter mile

https://www.caranddriver.com/reviews...t-reliability/

[Bimmerfun82]

Originally Posted by MisanoblueZ4

Also just a note.

C&D recently did an updated review of the M40i and clocked the fastest time yet of any publication (US version)

0-60 3.5s
1/4 mile 12.0 @ 116mph

75mph mpg’s 37

The Z4 M40i is a seriously quick sports car if you want that, I doubt the general public would have any idea they can scoot that quickly.

I have never gotten anywhere close to 37 mpg. Maybe downhill in eco pro from the mountains. Would love to know how they achieved this. And acceleration - I haven’t tried launch control, car is super quick without it but traction can be an issue. I’d say by the seat of my pants I can do 4.5s pretty easily.

[Horseman]

Originally Posted by ebirotedu

With the Dinan mods the graph shows 468 crank HP and 509 lb-ft of torque.

Dinan is using a 17% drivetrain loss correction factor to come up with that number looks like.

Without the mods they’re estimating 448hp and 450lb-ft torque at the crank.

That makes more sense to me now. Thank you.

[ebirotedu]

Yeah, peak HP can be used as a proxy for such things, but it's only a proxy.

Personally, I'm convinced that the B58 makes more than 400 HP, but not that it makes 450. But maybe it does.

Dinan has plenty of incentive to use a dyno that reads high considering that there's a marketing advantage to quoting the highest post-Dinan mod HP number they can.

Ultimately, whether we agree that the US spec M40i really makes 420 hp or 450, it won't make our cars any faster or slower.

Originally Posted by MisanoblueZ4

Trap speeds of 116mph in the 1/4 is certainly showing well over 400hp crank. Nearly 450ish is believable, this is a 3500lb car with less tire then a C7 Corvette and the Trap speeds are not far off.


Here is a 2017 Grand Sport test by C&D, 3.9 0-60 12.3@116 quarter mile

https://www.caranddriver.com/reviews...t-reliability/

[MisanoblueZ4]

Originally Posted by Bimmerfun82

I have never gotten anywhere close to 37 mpg. Maybe downhill in eco pro from the mountains. Would love to know how they achieved this. And acceleration - I haven’t tried launch control, car is super quick without it but traction can be an issue. I’d say by the seat of my pants I can do 4.5s pretty easily.

I’ve done 37 mpg returning from dealership after purchase on the highway CC set to 75. In adaptive mode I hit over 40 mpg on a round trip freeway with a 60mph speed limit….1.5hr round trip couple weeks ago. The flexibility of quickness AND excellent MPG’s is one of this cars best attributes.

Your Z4M40i with auto is capable of much better then 4.5 0-60. Once you get your manual it will be MUCH more difficult to be consistent getting out of the hole, your now not only battling traction issues but managing clutch release and nailing perfect shifts. But yes, the engagement factor of having to pull it all off perfectly can be fun…..miss a shift, blow the launch with too much wheel spin or bog and some of that fun goes away lol.
I always found my manual sports cars better at speed, going through gears, then being used off the line or drag raced.

[GerryC]

Originally Posted by Bimmerfun82

I have never gotten anywhere close to 37 mpg. Maybe downhill in eco pro from the mountains. Would love to know how they achieved this. And acceleration - I haven’t tried launch control, car is super quick without it but traction can be an issue. I’d say by the seat of my pants I can do 4.5s pretty easily.

I've had two trips that showed 37.2 mpg/62 mph average. Relatively flat US Hwy cruising at 65 mph. At 75 mph I get just under 35 mpg. I agree with you on the acceleration.

[Bimmerfun82]

Great efficiency, but have some fun every once in a while . Even on the highway I can't resist the occasional push.

[BEAR-AvHistory]

My best for a regular run with the robot at 85mph on the interstate portion,, may have slipped over that a bit on occasion. Over all trip a bit over 200 miles with 30 or so miles at controlled speeds as low as 50.

Trip can be variable depending on season or day of the week.





Best Dragy was 3.79/4.02 More typical is 3.95/4.29. Think Dinan loss factor is too high. Doubt the car has 450BHP at the crank pure stock.

Going out now but need to match the earlier C&D tests with the current one to try & get a base. IIRC the earlier tests were around 116mph but the times were about 2/10 slower.

[MisanoblueZ4]

Originally Posted by ebirotedu

Yeah, peak HP can be used as a proxy for such things, but it's only a proxy.

Personally, I'm convinced that the B58 makes more than 400 HP, but not that it makes 450. But maybe it does.

Dinan has plenty of incentive to use a dyno that reads high considering that there's a marketing advantage to quoting the highest post-Dinan mod HP number they can.

Ultimately, whether we agree that the US spec M40i really makes 420 hp or 450, it won't make our cars any faster or slower.

https://motorweek.org/road_tests/201...e-grand-sport/

Just to further that the Z4M40i is vastly underrated, these C7 Grand Sports have more tire, yet 0-60 similar and trap speed similar to Z4M40i.
Chevy rates them with 460hp 465tq

There is no way possible a Z4 with “only” 382hp would be able to overcome this 78hp and near 100tq deficit with less tire and perform equally unless it was substantially lighter.

Let’s look at that, C7 GS is 3464lbs, Z4 M40i is 3457….again the numbers don’t add up.

Anyway you look at it, the M40i is a very quick car and likely due to BMW wanting to keep the M cars levels higher in pecking order the B58 is given its hp figure well short of what it actually is.

Now imagine if they released the Z4 with (450hp) rating? Would that have given the Z4 more favorable initial reviews instead of how overpriced it is and how a Porsche is just a little more $$….. “Omg you get 450hp for 65k!!!!, that’s a steal”

It would not have hurt imo. But hey there are positives, perhaps lower insurance rates, some “sleeper” status, less tax (Europe)

[Bimmerfun82]

Better transmission?

[MisanoblueZ4]

Originally Posted by Bimmerfun82

Better transmission?

Manual and auto C7’s seem to have no significant difference in mag test times.

The Z4 auto is excellent, still working with allegedly 382hp, the trap speed does not equate to that level of hp.

[Bimmerfun82]

But what about auto C7 v ZF8 Z4? Traction and launch control and snappy shifts can make up for some of the delta..?

[MisanoblueZ4]

Originally Posted by Bimmerfun82

But what about auto C7 v ZF8 Z4? Traction and launch control and snappy shifts can make up for some of the delta..?

That can to help the car get off the line 0-60, once your looking at 1/4 mile trap speeds it’s a universal good benchmark for hp.
All the signs are there that the B58 in the Z4 M40i is factory underrated at the crank.

[BEAR-AvHistory]

Quick & dirty. all numbers pretty close but 2024 shows a consistent time advantage. Terminal speed remains the same at 116MPH suggesting 2024 may have a low/mid range tune change or gearing advantage.

Could also just be better conditions on the test day. Regardless the car is stronger than 382BHP. Point is all numbers are fudged by the manufactures for legal, insurance, competitive or internal brand marketing reasons.

True scale weight vs terminal speed would determine actual power.


C/D
TEST RESULTS - 7/12/23
60 mph: 3.5 sec
100 mph: 8.8 sec
[COLOR="red"]1/4-Mile: 12.0 sec @ 116 mph
130 mph: 15.4 sec
150 mph: 22.4 sec
Results above omit 1-ft rollout of 0.3 sec.
Rolling Start, 5–60 mph: 4.4 sec
Top Gear, 30–50 mph: 2.3 sec
Top Gear, 50–70 mph: 2.7 sec
Top Speed (gov ltd): 152 mph
Braking, 70–0 mph: 149 ft
Braking, 100–0 mph: 299 ft
Roadholding, 300-ft Skidpad: 1.00 g
Observed: 24 mpg
75-mph Highway Driving: 37 mpg

C/D
TEST RESULTS - 2/20/20
Rollout, 1 ft: 0.3 sec
60 mph: 3.7 sec
100 mph: 9.1 sec
130 mph: 15.8 sec
Rolling start, 5–60 mph: 4.5 sec
Top gear, 30–50 mph: 2.6 sec
Top gear, 50–70 mph: 2.8 sec
¼-mile: 12.2 sec @ 116 mph
Top speed (governor limited, C/D est): 165 mph
Braking, 70–0 mph: 148 ft
Roadholding, 300-ft-dia skidpad: 1.02 g

C/D FUEL ECONOMY
75-mph highway driving: 38 mpg
Highway range: 510 miles

EPA FUEL ECONOMY
Combined/city/highway: 26/24/31 mpg

C/D
TEST RESULTS 9/19/19
Zero to 60 mph: 3.8 sec
Zero to 100 mph: 9.1 sec
Zero to 130 mph: 15.9 sec
Rolling start, 5–60 mph: 4.5 sec
Top gear, 30–50 mph: 2.6 sec
Top gear, 50–70 mph: 2.8 sec
Standing ¼-mile: 12.3 sec @ 116 mph
Top speed (governor limited, C/D est): 165 mph
Braking, 70–0 mph: 148 ft
Roadholding, 300-ft-dia skidpad: 1.02 g

C/D
FUEL ECONOMY
Observed: 20 mpg

EPA FUEL ECONOMY
Combined/city/highway: 26/24/31 mpg

[dholaday]

Thanks for posting those data.

I know this must be a stupid question, but why are the 5-60 rolling start times 1 second longer than 0-60 [which I assume include a 1-foot rolling start]?

Thanks
Duncan