[driverman]

I THINK (but don't know for sure) that the main motivations for moving to turbo engines are that turbo engines of similar size and weight as NA engines can generate better fuel economy (mandated by many countries), more HP and more low end torque. Additional benefits include smaller engine packages and more in-house (and for enthusiasts 3rd party) tunability. The downsides are more cost and complexity needed to extract more power out of the same displacement. I see why BMW is doing it. Makes sense to me.

Even Honda is putting turbo engines in the upper models of the 2016 Honda Civic. The base engine is going to be a 2 liter NA 4 and upper engine a 1.5 liter turbo 4.

[Efthreeoh]

Originally Posted by driverman

I THINK (but don't know for sure) that the main motivations for moving to turbo engines are that turbo engines of similar size and weight as NA engines can generate better fuel economy (mandated by many countries), more HP and more low end torque. Additional benefits include smaller engine packages and more in-house (and for enthusiasts 3rd party) tunability. The downsides are more cost and complexity needed to extract more power out of the same displacement. I see why BMW is doing it. Makes sense to me.

Even Honda is putting turbo engines in the upper models of the 2016 Honda Civic. The base engine is going to be a 2 liter NA 4 and upper engine a 1.5 liter turbo 4.

I think turbo engines meet fuel efficiency and emission mandates in the test environment, but in real use offer no real benefit. They do allow for better tuning of torque curves however.

[aohus]

I hope my N54 gets to 300,000 miles. I absolutely love the car. I've been neglecting it for 5 years until I ran into a minor issue and repaired it on my own. Since then I've been spending a bit trying to DIY as much as I can and I've grown more attached to the car.

Started with the K&N filter, to DIY'ing the cup holder, then to spark plugs, oil change, and cleaning the interior leather.

Crazy that I never really got into maintaining the car (I did have 4 year 50k warranty) until now.

Stretch goal is to replace the valve cover gasket + replacing the diff and trans fluid. Don't have a lift though :/

Right now I have a Passport Max Radar Detector on order as well as the PCV Valve + Oil Catch Can. Dashcam installed (A118C).

[krhodes1]

Originally Posted by Efthreeoh

I think turbo engines meet fuel efficiency and emission mandates in the test environment, but in real use offer no real benefit. They do allow for better tuning of torque curves however.

My ownership of a bunch of turbo Saabs and now a turbo BMW says you are wrong. Despite 90+ more hp, my M235i gets basically the same gas mileage as my e9x 328i in the real world. A 228i gets so much better gas mileage than an e9x 328i it isn't even funny, while still being faster.

Some automakers can't seem to get turbos quite right - Ford seems to be able to get the power but not the real world economy, as an example. Saab cracked it a long time ago, and BMW very much knows what they are doing too.

The downside is added complexity of course. TANSTAAFL... Though I have owned enough turbo cars with extremely high mileage to not be particularly afraid of it.

[Efthreeoh]

Originally Posted by krhodes1

My ownership of a bunch of turbo Saabs and now a turbo BMW says you are wrong. Despite 90+ more hp, my M235i gets basically the same gas mileage as my e9x 328i in the real world. A 228i gets so much better gas mileage than an e9x 328i it isn't even funny, while still being faster.

Some automakers can't seem to get turbos quite right - Ford seems to be able to get the power but not the real world economy, as an example. Saab cracked it a long time ago, and BMW very much knows what they are doing too.

The downside is added complexity of course. TANSTAAFL... Though I have owned enough turbo cars with extremely high mileage to not be particularly afraid of it.

Unless one keeps strict records of fuel mileage over long periods, and most people don't (I do however), it's been my experience that MPG statistics are merely conjecture. I also know that one of my buddies had a WRX STI (last gen) with 300 HP, and found the car got no better real world fuel mileage than the EPA rating of the 300 HP Mustang GT of the same vintage. I have a friend now that has a Ecoboost Fusion and is not happy with the real world fuel mileage (19 overall), and he's no hotrodder by any means, he just drives it like a car.

Your experience I'll not doubt since I have no data to counter it, but my question I do have is with the added maintenance and repairs (costs) that are indicative of a turbo engine simply because they are more complex, is the fuel mileage gain economically viable as compared to a NA engine? Meaning does the fuel cost savings still put you ahead in total long term vehicle operating cost as compared to a NA engine. It is my belief that the fuel costs savings is offset by the added maintenance costs/repairs.

The chemist in me knowing that the engine tries to achieve the best stoichiometric chemical reaction to conserve fuel means the fuel/air ratio is basically the same for any engine making similar horsepower. Granted that combustion chamber design can somewhat affect the chemical reaction (combustion process) inside the cylinder and that other engine design parameters affect the vehicles fuel consumption performance, but it's all quite close between modern automotive engines. Which leads me to consider that turbo engines can be tuned to meet strict Government fuel consumption tests better than non-turbo motors, but in real world use the gains are not that great, and combined with added maintenance costs, is not worth it.

Car & Driver recently did a comparo of this sort with the Honda Civic and came found these results and this conclusion:

"By the EPA’s measure, the turbo Civic holds a 1-mpg edge on the highway with its 31/42-mpg ratings."

"On a 300-mile loop of mixed highway, rural, and urban driving, the cars proved equally frugal by averaging 40 mpg. Digging deeper, we measured the steady-speed fuel consumption of the two Civics. Some of our results are astounding, such as the 50-plus-mpg both Civics achieve at 55 mph. The turbo wins across speeds ranging from 30 to 90 mph, with a 6-mpg advantage between 40 and 55 mph."

"Spending the extra $1160 for the Honda’s turbo engine does have one clear advantage beyond efficiency: The additional power and torque clip 1.4 seconds from the zero-to-60-mph run and a full second off the quarter-mile time compared with the naturally aspirated alternative. But exceed the gentle, twinkle-toe throttle pressure we applied in our steady-speed tests and all efficiency bets are off. As boost rises, more fuel is injected and mileage drops. Precipitously."

To me the added cost of the turbo engine and probable increased maintenance costs of the turbo don't achieve an economic advantage over a non turbo motor via fuel consumption savings.

[John 070]

Originally Posted by Efthreeoh

To me the added cost of the turbo engine and probable increased maintenance costs of the turbo don't achieve an economic advantage over a non turbo motor via fuel consumption savings.

If this were true, why is nearly every car co. deploying them?

We get it, you're playing the devil's advocate and trying to be old school. That's fine because up to that point, it's subjective, but to get into economics is kind of pushing it. Car cos. are all about profit, like banks.

In the real world, a 2016 328i x drive auto gets 26 mpg on my commute. My 335i RWD gets 21.7. Every 328i x-drive loaner I have gotten over the years got 17.x. These are real numbers, valid and reliable as they are over a 6 yr. period and each number is over 4 weeks or longer.

p.s. you do know there are smartphone apps that make it really easy to keep mpg numbers over years across multiple phones as you move the database easily as well?

[John 070]

Originally Posted by aohus

I hope my N54 gets to 300,000 miles. I absolutely love the car. I've been neglecting it for 5 years until I ran into a minor issue and repaired it on my own. Since then I've been spending a bit trying to DIY as much as I can and I've grown more attached to the car.

Started with the K&N filter, to DIY'ing the cup holder, then to spark plugs, oil change, and cleaning the interior leather.

Crazy that I never really got into maintaining the car (I did have 4 year 50k warranty) until now.

Stretch goal is to replace the valve cover gasket + replacing the diff and trans fluid. Don't have a lift though :/

Right now I have a Passport Max Radar Detector on order as well as the PCV Valve + Oil Catch Can. Dashcam installed (A118C).

My first "MAJOR" issue on the 335i was the DSC Hydro failing, I hear it's a $3,400-$3,800 (part has gone up again by $300) job at the dealer, and thank goodness the DIY is <$300. That has nothing to do with turbocharging. Other than that, nothing required repair-wise except the vanos solenoids, again, nothing to do with turbocharging.

I get that purists are against it, and feel somehow it's "unfair" to get full torque at 1300 rpm up to about 5000 rpm, it's just not the way they learned to drive. And what they like is what they like. But some of the comments are plain nuts!

Again, the 991.2 911 is turbocharged, so one could say, the fat lady sung. Just don't call a Carrera or Carrera S a "turbo," even though it's got two. Turbo is reserved for the iconic 911 Turbo.

[Antetokounmpo]

Totally agree with OP on this one. Companies are going turbo for gov't/EPA restrictions. However, in the real world, the cars really don't get any better fuel economy. It's not rocket science, to produce x amount of power, you need y amount of fuel. The engine does not care if it's compressed or atmospheric pressure. Now, if you are the EPA and test the cars without even hitting boost, then yes they will get better fuel mileage (to put on the window sticker and avoid taxes). But once the driver starts actually driving like a normal human, hitting boost once or twice a day, the fuel mileage drops significantly, usually equaling out NA engines. Just look at the F150, owners complain about the ecoboost V6 getting worse mileage than the V8 in the real world.

[John 070]

Originally Posted by Heel Toe

Totally agree with OP on this one. Companies are going turbo for gov't/EPA restrictions. However, in the real world, the cars really don't get any better fuel economy. It's not rocket science, to produce x amount of power, you need y amount of fuel. The engine does not care if it's compressed or atmospheric pressure. Now, if you are the EPA and test the cars without even hitting boost, then yes they will get better fuel mileage (to put on the window sticker and avoid taxes). But once the driver starts actually driving like a normal human, hitting boost once or twice a day, the fuel mileage drops significantly, usually equaling out NA engines. Just look at the F150, owners complain about the ecoboost V6 getting worse mileage than the V8 in the real world.

tell this to people driving n20/n26's. They are clearly getting better fuel economy than N52s, like you said, it's not rocket science. Is it as smooth? No way. We can debate it until the sun goes down, and what we like is what we like, but the industry marches on. My grandpa says real Porsches are not liquid cooled. But the car co. didn't listen to him.

We've known for 9+ years that 335's usually get better mpgs than 328's in the real world, I've heard DI was to blame. But the end result is what it is.

edit: The EPA isn't testing cars, the car mfgs. are self reporting. The EPA years ago only tested 15% of all cars. When the F30 came out, BMW slapped a 36 highway number on it, and immediately the EPA tested one and said no, you will put 33 on the window. Because BMW is not an American co. Again, on extended loaner periods, I easily got 40 mpg hwy with a 335d, and with the '16 328, 38 on the highway. My 335i is struggling to do 30, but maybe a walnut blast may help.

[krhodes1]

Originally Posted by Efthreeoh

Unless one keeps strict records of fuel mileage over long periods, and most people don't (I do however), it's been my experience that MPG statistics are merely conjecture. I also know that one of my buddies had a WRX STI (last gen) with 300 HP, and found the car got no better real world fuel mileage than the EPA rating of the 300 HP Mustang GT of the same vintage. I have a friend now that has a Ecoboost Fusion and is not happy with the real world fuel mileage (19 overall), and he's no hotrodder by any means, he just drives it like a car.

Your experience I'll not doubt since I have no data to counter it, but my question I do have is with the added maintenance and repairs (costs) that are indicative of a turbo engine simply because they are more complex, is the fuel mileage gain economically viable as compared to a NA engine? Meaning does the fuel cost savings still put you ahead in total long term vehicle operating cost as compared to a NA engine. It is my belief that the fuel costs savings is offset by the added maintenance costs/repairs.

The chemist in me knowing that the engine tries to achieve the best stoichiometric chemical reaction to conserve fuel means the fuel/air ratio is basically the same for any engine making similar horsepower. Granted that combustion chamber design can somewhat affect the chemical reaction (combustion process) inside the cylinder and that other engine design parameters affect the vehicles fuel consumption performance, but it's all quite close between modern automotive engines. Which leads me to consider that turbo engines can be tuned to meet strict Government fuel consumption tests better than non-turbo motors, but in real world use the gains are not that great, and combined with added maintenance costs, is not worth it.

Car & Driver recently did a comparo of this sort with the Honda Civic and came found these results and this conclusion:

"By the EPA’s measure, the turbo Civic holds a 1-mpg edge on the highway with its 31/42-mpg ratings."

"On a 300-mile loop of mixed highway, rural, and urban driving, the cars proved equally frugal by averaging 40 mpg. Digging deeper, we measured the steady-speed fuel consumption of the two Civics. Some of our results are astounding, such as the 50-plus-mpg both Civics achieve at 55 mph. The turbo wins across speeds ranging from 30 to 90 mph, with a 6-mpg advantage between 40 and 55 mph."

"Spending the extra $1160 for the Honda’s turbo engine does have one clear advantage beyond efficiency: The additional power and torque clip 1.4 seconds from the zero-to-60-mph run and a full second off the quarter-mile time compared with the naturally aspirated alternative. But exceed the gentle, twinkle-toe throttle pressure we applied in our steady-speed tests and all efficiency bets are off. As boost rises, more fuel is injected and mileage drops. Precipitously."

To me the added cost of the turbo engine and probable increased maintenance costs of the turbo don't achieve an economic advantage over a non turbo motor via fuel consumption savings.

You are completely correct - 300hp requires 300hp of gas - but you are very rarely using 300hp when driving day-to-day. You have picked a notoriously inefficient example - the WRX has Subaru's generally inefficient boxer engine and AWD which drag down the mileage of even the non-turbo versions. Big V8s in relatively light tall-geared cars do surprising well on highway mileage at least. Turbos allow taller gearing and a smaller engine to do the work of a larger one. Taller gearing pays on the highway, smaller engine pays for all part-throttle operation. Ultimately foot to the firewall it won't make much difference either way.

In the long run, maybe turbos pay on a strictly dollars and cents basis, and maybe they don't - I've owned a dozen or more turbo cars and have never had an issue worse than replacing a vacuum hose related to the turbochargers. Don't take the experiences of early x35i BMW owners as the norm. In the short run they generally provide a more satisfying driving experience (as shown by your Honda example), and I would rather potentially pay a mechanic, than definitely pay at the pump every week. And of course, driving style plays into it considerably. I much prefer the ability to use low revs to make decent progress than having to rev the nuts off an engine. Which is pretty much the difference between an N20 and an N52.

As I said for real world vs. "the test" some makes have it down, and some don't. Ford definitely doesn't. BMW certainly does, and Saab did. Volvo and Mercedes seem to be doing it right too. As a long time Saab fan and multiple serial owner, I find it hilarious that the formula that Saab was denigrated for for so many years is now the new normal. The ~2.0T 4-cylinder is the way to go for power and efficiency now.

[John 070]

I understand...many of us here prefer sticks, I do. Someone can say, but the DCT can shift in ms, you can't shift that fast, a DCT can spank you on a track. We still prefer a stick. Part of my commute is bumper to bumper, from 0 to 3 mph. I still prefer a stick under these conditions. But these days I am driving a '16 328 x-drive--I hate having an auto, and it's one case where I turn off the ASS feature.

By the same token, many prefer NA cars, they dislike and don't want turbos. Nothing wrong with that. If anyone qualifies to be a purist, imho someone who is spending 140k on a new 911 does. Or, they are rich mothas. They of all people should dislike twin turbos and cars with electric power steering. Yet, most love the 991.2, which is a Porsche, and has both of the above.

Again, I understand if you don't like turbos. Perfectly valid. But to say they have no purpose....every single truck/rig you pass on the highway is a) an inline 6 b) turbocharged And these are all business, no pleasure

I notice that even on a forum such as this, where people have the capability to completely rebuild their car in their home, there is still a tendency to dwell on HP, and not torque. Madison Ave. really proves they are king. HP, as does sex, sells.

One feature I notice in the F80 is the screen that shows HP/torque at a given slice of time. I don't have such a thing on my 335i. imho it does reveal a lot about this conversation.

[Antetokounmpo]

Originally Posted by John 070

tell this to people driving n20/n26's. They are clearly getting better fuel economy than N52s, like you said, it's not rocket science. Is it as smooth? No way. We can debate it until the sun goes down, and what we like is what we like, but the industry marches on. My grandpa says real Porsches are not liquid cooled. But the car co. didn't listen to him.

We've known for 9+ years that 335's usually get better mpgs than 328's in the real world, I've heard DI was to blame. But the end result is what it is.

edit: The EPA isn't testing cars, the car mfgs. are self reporting. The EPA years ago only tested 15% of all cars. When the F30 came out, BMW slapped a 36 highway number on it, and immediately the EPA tested one and said no, you will put 33 on the window. Because BMW is not an American co. Again, on extended loaner periods, I easily got 40 mpg hwy with a 335d, and with the '16 328, 38 on the highway. My 335i is struggling to do 30, but maybe a walnut blast may help.

There are many reasons the N20 gets much better fuel mileage versus the N52. Eight speed transmission, direct injection, etc. Heck, the N54 can get the same mileage as the N52. If bmw kept a NA I6 around and updated it with the newest technology, I almost guarantee you it would get the same mileage as the N20. Just look at the 340i, 3.0L turbo gets within 1mpg city and 2mpg highway of the N20. Take the turbo off and it'd probably be identical to the N20.

[Efthreeoh]

Originally Posted by Heel Toe

There are many reasons the N20 gets much better fuel mileage versus the N52. Eight speed transmission, direct injection, etc. Heck, the N54 can get the same mileage as the N52. If bmw kept a NA I6 around and updated it with the newest technology, I almost guarantee you it would get the same mileage as the N20. Just look at the 340i, 3.0L turbo gets within 1mpg city and 2mpg highway of the N20. Take the turbo off and it'd probably be identical to the N20.

Friend of mine at work has a 2010 328i, no ZSP, just plain jane 3-series. She had it in at the local dealer for service last week and got a F30 320i as a loaner. Keep in mind this lady is not a car enthusiast by any stretch, but she is an engineer however. Unsolicited comment from her, she thought the F30 totally sucked in handling and engine performance as compared to her E90. She especially commented about the engine (N20) and how it made no power and was very noisy. She knew the F30 had a 4-cylinder turbo. She was quite unimpressed...

[beri486]

Originally Posted by beri486

I also drive a 325i E90 with close to 151K on it, bought new in Aug. 05. It's an automatic though. I drive at least 400 miles a week 95% on the freeways.

The only major repair was an oil leak at around 120K and replacing spark plugs and a coil at around 138K. I also had to replace both rear window regulators at 92K and 135K.

The car runs excellent, I change oil & filter every 5000 miles or so.

I intend to drive it until it hits 222222

I am now at 200K+, the car will be 11 years old in August.
And it is still running on the original water pump!!!!

[tlow98]

I think in the light of the recent diesel-gate scandal and mag comparisons it's clear the turbo does not hold every advantage. Especially, not nearly as much as the automakers would love to have you believe. It's an incrimental change to mpg, offers more torque and at the same Time more complexity.

I don't think there's anything 'old school' about NA engines considering forced induction has been around for 100 years, but turbos are a technology that's been perfected recently that helps automakers maintain or exceed performance levels with engine capacity financial restrictions (taxes) in most places around the world.

The fact that the Japanese manufacturers are a hold out until recently does not surprise me. They rarely ever make a decision that does not make financial sense or isn't forced upon them by market pressures. Of course, I think it's the latter in this case, but I'm bias

[Illoosive]

I honestly hope my car makes it, just trying to keep it updated as possible and biking to work now to extend the life of my dear friend.

[Richwm]

I made it to 200,000 yesterday.

[Richwm]

200,000 and still running strong.

[Efthreeoh]

Originally Posted by Richwm

I made it to 200,000 yesterday.

Congratulations! For a while there (way back) we were running neck and neck to 200K, but I think you started driving another car.

Here's to another 100K.

[5tony]

My e90 has only 58K miles. By the time it reaches 200K, we'll be talking about the new 3 series hybrid with a small turbocharged engine and electric motors at each wheel.

[galahad05]

Mine has just a tick over 106,000 miles. It definitely uses oil...like a quart every 2k miles.

I do have to say though, that I haven't opened up my oil catch can in tens of thousands of miles; an OCC-caused PCV backup would cause excessive oil consumption. I'll be checking this weekend.

[Wilt]

Originally Posted by krhodes1

My ownership of a bunch of turbo Saabs and now a turbo BMW says you are wrong. Despite 90+ more hp, my M235i gets basically the same gas mileage as my e9x 328i in the real world. A 228i gets so much better gas mileage than an e9x 328i it isn't even funny, while still being faster.

1. The 2015 M235i is listed at 3505 lbs. unladen weight, while the 228i weighs in at 3250 lbs. In contrast the E90 (2011) is listed at 3362 lbs. So the M235i has a weight advantage over the 328i, which does translate to a bit more fuel economy.
   
2. But far more importantly, the 228i final drive ratio is high at 3.08:1, compared to the 328i having much lower 3.73:1, both cars spec for A/T...228i turns 21% less per mile.

That reflects in 23/36mpg vs. 18/28mpg claims by BMW for the two cars.