DIESEL: Is the 4k worth it? It depends.....

[Fraser]

Originally Posted by grover432

That deal just tells you where the dealer and BMW think the value for the V8 is going to be once the 35d gets here. As for performance of the diesel vs the V8, I can believe the Aussie review above. Top Gear tested a BMW 535d and I believe if beat an M5 to 40 mph. Most vehicles seem to have either high HP (they are blisteringly fast once they get going), or high torque (and they move incredibly fast off the line. At some point the two designs intersect. So, off the line and to say 40 mph the 35d will likely outperform the 4.8, after that the 4.8 will pass the 35d and keep going.

Don't laugh at this comparison, but my only experience with diesel was a 2004 Dodge 3/4 Ton Ram pickup. It had something like 525 lb. ft of torque and 285 hp. I'm not one to race from stoplight to stoplight, but when I wasn't pulling a trailer and found myself in the curb lane waiting for a light to turn green - cars parked in the curb lane ahead - I never got beat to 35 mph by anything that was stopped to the left of me (OK, Porsches, etc. not included). And the truck did it effortlessly. My only gripe? Turbo lag.

I'm reserving judgement until I drive the diesel as well. But having come from one, I'm expecting great things and as far as usable performance, I totally understand where the Aussie is coming from.

With the 35d, turbo lag, or anything that counts as turbo lag, just doesn't exist. Unlike the twin turbo diesels from Audi, VW, Land Rover, Toyota, or Jaguar, where each of their equal size turbos feeds a bank of either four or five cylinders in their respective V8 or V10 engines, and therefore work in independently in parallel, not helping each other, the twin turbos in BMW's 35d straight six work as as a team, sequentially. There's a small turbo (with little inertia) that gets things going off idle, and a big one (that can blow hard) that takes over once the things are underway. The two seamlessly interact, or that's at least as the Aussie spec twin-turbo diesels work.

[JCL]

Originally Posted by Fraser

With the 35d, turbo lag, or anything that counts as turbo lag, just doesn't exist. Unlike the twin turbo diesels from Audi, VW, Land Rover, Toyota, or Jaguar, where each of their equal size turbos feeds a bank of either four or five cylinders in their respective V8 or V10 engines, and therefore work in independently in parallel, not helping each other, the twin turbos in BMW's 35d straight six work as as a team, sequentially. There's a small turbo (with little inertia) that gets things going off idle, and a big one (that can blow hard) that takes over once the things are underway. The two seamlessly interact, or that's at least as the Aussie spec twin-turbo diesels work.

I don't disagree with your comment that there is no perceptible turbo lag with the 35d, but it isn't because of the sequential turbos, it is because of careful turbo matching and design. Try driving a 35i, which has a parallel turbo arrangement, and you will find no turbo lag.

All of this discussion about the 35d having more torque and being much more drivable than the 4.8 is missing the mark, in my opinion. People are comparing naturally aspirated engines and turbo engines, and concluding that the differences are due to the gasoline or diesel fuel, when the differences are in fact due to the turbos. Look at the torque figures for the 35i compared to the 35d; the gasoline engine has peak torque at 1300 rpm, instead of 1900 rpm. That makes it more drivable than the diesel, and better suited for towing. No, it doesn't have the same peak torque, but if that is what you need then look at the 4.4 twin turbo.

[grover432]

Originally Posted by JCL

I don't disagree with your comment that there is no perceptible turbo lag with the 35d, but it isn't because of the sequential turbos, it is because of careful turbo matching and design. Try driving a 35i, which has a parallel turbo arrangement, and you will find no turbo lag.

All of this discussion about the 35d having more torque and being much more drivable than the 4.8 is missing the mark, in my opinion. People are comparing naturally aspirated engines and turbo engines, and concluding that the differences are due to the gasoline or diesel fuel, when the differences are in fact due to the turbos. Look at the torque figures for the 35i compared to the 35d; the gasoline engine has peak torque at 1300 rpm, instead of 1900 rpm. That makes it more drivable than the diesel, and better suited for towing. No, it doesn't have the same peak torque, but if that is what you need then look at the 4.4 twin turbo.

I assume you are talking about the engine in the 335i (X6)? Doesn't it also have sequential turbos? It only has 300 lb ft. albeit at 500 rpm lower, as opposed to 425 lb. ft. I believe the difference in the seat of the pants will be noticeable. Also, when you compare the fuel mileage of the 2 engines, the 335i is rated at 14.7L/100 City, which is much higher consumption with the diesel. There is no question that the 35d produces the torque it does because of the turbos, but that's Ok with me, as long as it has the torque.

As for pulling, I'll take the higher torque number at +500 rpm. You'll never notice the difference in where the peak torque is when the difference in peak is 500 rpm. Also, I think you'd have to take a look at the torque curves. I'm betting the 35d is producing more than 300 lb. ft. at 1,300 rpm.

This diesel is a great development - now if the cost of diesel didn't wipe out the economics ...

[Craig]

Diesel here is only about 45 cents more per gallon than premium unleaded.
It looks like I'm the only one that has one on order. I hope I don't end up with a lemon.

Craig

[JCL]

Originally Posted by grover432

I assume you are talking about the engine in the 335i (X6)? Doesn't it also have sequential turbos? It only has 300 lb ft. albeit at 500 rpm lower, as opposed to 425 lb. ft. I believe the difference in the seat of the pants will be noticeable. Also, when you compare the fuel mileage of the 2 engines, the 335i is rated at 14.7L/100 City, which is much higher consumption with the diesel. There is no question that the 35d produces the torque it does because of the turbos, but that's Ok with me, as long as it has the torque.

As for pulling, I'll take the higher torque number at +500 rpm. You'll never notice the difference in where the peak torque is when the difference in peak is 500 rpm. Also, I think you'd have to take a look at the torque curves. I'm betting the 35d is producing more than 300 lb. ft. at 1,300 rpm.

My 35i is in a 535, not a 335, but it is the same engine. No, the petrol 3.0 twin turbo does not have sequential turbos, it has parallel turbos as I said above (one for each three cylinders).

No argument that the 35d produces the torque because of the turbos, but if you take that one step further it is not because it is a diesel. Twin-turbo petrol engines have similar characteristics.

If you want more torque than the torque peak of the 35i (at 1300 rpm) then look at the 4.4 twin turbo, as I said.

Would be interested if you have a torque curve for the diesel, and not just the peak torque figure.

[DBC]

I disagree, diesel produces more torque because of the greater compression ratio, look back at before all diesels were turbo'd. A Gardner ( a great British engine) produced loads of torque compared to power. A 6XLB was rated at 180 BHP and 600+ lb ft of torque, all down to the high compression ratio and that derv has a higher callorific value than petrol.

I think you americans should stop fantacising and wait until you have driven a 3.0sd, having had the engine in first a 535d Sport and noe a X% 3.0sd, i can tell you that the driving experience delivered is far superior to anything a petrol of ant configuration can deliver. Why is almost all UK and Europe's for that matter diesel powered, it is not that we are all misers but we know a good drive when we have experienced it.

I notice also on the sister X6 forum that there is concern about warm up time on diesels. This may have been a factor in the past due to the greater thermal efficency of the diesel engine, (less heat is wasted to the coolent) but with thermostasic fans and BMW's efficency Dynamics wher the grill is close untill cool air is needed, i would sugest this id now no longer a problem.

[DBC]

I disagree, diesel produces more torque because of the greater compression ratio, look back at before all diesels were turbo'd. A Gardner ( a great British engine) produced loads of torque compared to power. A 6XLB was rated at 180 BHP and 600+ lb ft of torque, all down to the high compression ratio and that derv has a higher callorific value than petrol.

I think you americans should stop fantacising and wait until you have driven a 3.0sd, having had the engine in first a 535d Sport and noe a X% 3.0sd, i can tell you that the driving experience delivered is far superior to anything a petrol of ant configuration can deliver. Why is almost all UK and Europe's for that matter diesel powered, it is not that we are all misers but we know a good drive when we have experienced it.

I notice also on the sister X6 forum that there is concern about warm up time on diesels. This may have been a factor in the past due to the greater thermal efficency of the diesel engine, (less heat is wasted to the coolent) but with thermostasic fans and BMW's efficency Dynamics wher the grill is close untill cool air is needed, i would sugest this id now no longer a problem.

[JCL]

Originally Posted by DBC

I disagree, diesel produces more torque because of the greater compression ratio, look back at before all diesels were turbo'd. A Gardner ( a great British engine) produced loads of torque compared to power. A 6XLB was rated at 180 BHP and 600+ lb ft of torque, all down to the high compression ratio and that derv has a higher callorific value than petrol.

I think you americans should stop fantacising and wait until you have driven a 3.0sd, having had the engine in first a 535d Sport and noe a X% 3.0sd, i can tell you that the driving experience delivered is far superior to anything a petrol of ant configuration can deliver. Why is almost all UK and Europe's for that matter diesel powered, it is not that we are all misers but we know a good drive when we have experienced it.

The greater torque isn't because of the compression ratio. It is because of the longer stroke (which also limits the rpm). That long crank arm is what makes the torque. You can use a short stroke, and a smaller combustion chamber, to achieve the same compression ratio, but then you wouldn't have much torque.

I know something of the Gardner engines, but I would struggle to put them in the 'great' category in a current (modern day) discussion. You like the Mirlees Blackstones as well?

If you are referring to heating value (calorific value) then petrol is higher than diesel, as I recall. It is just that a diesel engine can extract more energy due to the higher compression ratio.

Almost all UK vehicles are diesel because of government tax structures on diesel fuel, not inherent superiority. That tax structure has encouraged manufacturers to further develop automotive diesels, and they are efficient appliances, no doubt. They just have no soul IMO.

PS: If you call me an american, I will come and hit you with both my Canadian and UK passports

[DBC]

JCL

As i recall when i was at college 1 gallon of derv had more callorific value than i gallon of petrol.

I stated that Gardner was an engine of the past, a Great British one only to state that diesels without turbos have a much higher torque to power ratio, the turbo only multiplies this both power and torque due to more air being forced into the cylinder so more fuel can be injected hence more power.

As for your argument regarding tax, RUBISH, the diesel X5 makes a much better drive than any petrol, it would probably be cheaper to fuel a petrol one here in the Uk at the moment petrol being 15p a litre cheaper than derv and Alister darling would only want another £120 a year in Road Fund over 12000 miles a year there would be something or nothing in the economics of running either, just the diesel and the sync turbo sd is a much better car and i sugest you try one that has at least 6000 miles on before making any judgements.

[tim-atl]

Originally Posted by Craig

Diesel here is only about 45 cents more per gallon than premium unleaded.
It looks like I'm the only one that has one on order. I hope I don't end up with a lemon. Craig

since things are heating up.....

Unless you want to drive 30 miles in some random direction to find the cheapest fuel, we're at 60 cents here in the Atlanta area, which is better than it has been but still pretty sucky (premium compared to diesel). Personally, My reasons for wanting a diesel have nothing to do with the cost of fuel but paying that much more does bother me. It's principle more than budget, I completely despise the predatory oil industry.

So, we'll get back on topic and then I'll rant some more. This has been a really good thread and I hope we can keep it going.

Craig - I should just speak for myself but I think many of us are silently waiting for your "First Impressions in my new X5 xDrive35d" thread. I know I am. Before our friends in other county's who have the SD chime in that it's not new, I think all that adblue crap is new and we'll have to see how it works out (I'm using the word "crap" affectionately). I will probably order one myself but am waiting on some things:

your thread

New iDrive

Let's all take off the rosy colored BMW glasses and admit the old system sucked. Not just compared to today's stuff but it always sucked. The added buttons are what make the new system usable. I rented an Audi in Europe for a couple weeks last summer and loved their system. I'm specifically referring to the physical ergonomic portion, my opinion on the UI and features is neutral. BTW, the Audi was a diesel (and a station wagon) AND I loved it! I didn't expect to but holy shit.. for my fellow Americans, you don't know what we're missing.

This will be the third time I'm trying to buy a BMW. The dealerships are a huge problem. For some f*cked up reason, they think they are doing me a favor by selling me a BMW. I know these are luxury automobiles but I do work hard for my money. Tip for any CA's reading this - don't treat me like I have sucker stamped on my forehead. I expect that at domestic and non luxury foreign dealerships but NOT a BMW dealership.

The other problems I am having trouble getting over are:

the issues that go unfixed - back up camera for one, squeaky rear hatch for another

the nickel and diming on the options - CA $1000? Heated front seats $500? For a SAV with a base MSRP of $50Kish these really should be standard items. Yes, I realize some of you folks in other country's pay even more for your BMW's making my point double valid.

I love reading these forums but the crowd that continually makes excuses for BMW's shortcomings need to see one of those guys that breaks people from their cults. "There's a lot of technology in this car" and "it's a new model" are not acceptable answers for cars that cost as much as bimmer's do.

Ok, that's all. I'm really not a hater and have high expectations for the new X5sd but I guess my point is, if it doesn't meet my expectations I'm not going to buy it just to say I drive a BMW. Don't get me wrong, I really do want one. The X5 is simply the best looking SUV (SAV - whatever) out there and I hope to own one this spring.

Flame suit on, fire away!

Tim