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

[Craig]

Tim, I agree with you about the options. Porsche is worse than BMW. They charge for everything. They even charge for footwell lighting. When I ordered my 996tt back in 2002, I couldn't believe it. I did order the heated seats and comfort access, but felt like they should have been standard, not an option. You can buy a Nissan Altima and I don't know what they call their comfort access, but it's standard on a car that starts at less than $20K. I will let everyone know how it drives when I take delivery. I think dealers will have demos around December 15th. There is a 1555.00 IRS tax credit for the diesel X5.

Craig

[tim-atl]

Footwell lighting? Wow, guess I'll shut up about the options.

You know, the more I think about it, between my BMWCCA discount and the tax credit I may do alright.

I've been meaning to google the tax credit, is that $1550 deducted from my taxable income or am I actually getting $1550 back?

Tim

[tim-atl]

answered my own question here:

http://www.smartmoney.com/personal-f...-credit-23794/

"Remember that a buck worth of credit is much more valuable than a buck worth of deduction--because a credit reduces your federal income tax bill dollar for dollar"

The Merc's are listed but not the Bimmer's. I suppose it's because the article is from September.

Tim

[Craig]

Tim, I'm also going to receive the $1000.00 credit from my BMWCCA membership. The footwell lighting was like 740.00. I didn't order it. It was a light bulb on each side under the dash, so when you opened the doors, you could see your feet LOL! I thought I made a pretty good deal on the diesel. The longer I waited, the price kept coming down. One dealer started at MSRP and I told them to take me off their list. They called back about a week later to let me know they would offer a small discount. I told them, I don't want a small discount, I want a big discount. I ordered it out of town, not from my local dealer. This is my 4th BMW, and I haven't been able to purchase any from my local dealer. They have one coming in that's not sold. They said, we have a list of buyers if you don't want the car. I said OK, call someone else. They only have allocation for one diesel for the whole model year.

Craig

[grover432]

On the issue of diesel performance, fuel economy is it worth it? I think the point made by BMW in this piece from Edmunds (at the LA Auto Show) is interesting:

"The 2009 X5 xDrive35d, er, diesel X5, comes in at $52,025, but since the base X5 lacks the company's twin-turbo gasoline inline-6, the price jump is easier to swallow. BMW says the diesel X5 will hit 60 mph in 6.8 seconds -- as quick as the V8 X5. Rated at 19 city/26 highway, it's vastly more efficient than any other BMW X5 past or present."

So for those opting for the 4.8, I say this. You get a vehicle (35d) that will all but match the 4.8 in acceleration and best the fuel economy by 40%+ on an mpg basis. After you adjust for cost, you'll still be 20% ahead, with a vehicle that costs $7,000CAD less than the 4.8. That's why they are going to sell and have better residuals than the 4.8. It get my provisional (until I drive it) vote.

[Fraser]

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 agree that comparing a turbocharged diesel engine to a naturally aspirated petrol engine is technically unfair, but in this thread where the relative merits of the X5 engine options, ie. two naturally aspirated petrols and one turbodiesel, are under discussion, the comparison is 100 percent valid.

As for the relative merits of the twin turbo systems of 35i and 35d, saying that the 35i doesn't have lag therefore the sequential turbos of the 35d aren't designed to minimise lag is like saying a horse has four legs, therefore all things with four legs are horses.

With these two twin-turbo engines, the inherent differences between diesel and petrol engines come into play. BMW's naturally aspirated petrol six already makes reasonable top-end power but lacks low-down torque. The bottom end torque can be helped easily via turbo-charging and provided you don't want lots more power, mild (low-blow) turbocharging will do the job nicely, in this case by two very small, low interia turbos that spin up really quickly. As you say the 35i has already reached max torque by 1300rpm. Peak power however only jumps something like 12 percent. BMW could have jumped the power by 50 percent or better by using bigger turbo(s) but that risks introducing lag unless more sophisticated technology like sequential turbo charging or variable vane turbos is used.

In the case of the 35d, it would be next to useless without turbocharging. A three-litre atmo diesel would be doing well to make half the power of the 35d. The 35d enjoys this big power jump as its main turbo is a relative wopper and it needs its smaller mate to kick things off at the bottom end of the rpm range. It's more of a case of the diesel needing the extra sophistication of sequential changing while the petrol can get away with simpler parallel twin turbos.

It would be nice to have all the X6 engine options, especially the twin-turbo 4.4, in the X5. It can't be long off. Here's hoping!