X5 E53 is very competent vehicle for towing.I have never towed with 3/4 or 1 ton truck,but i can bet that my 4.6is had a better handling,better brakes and better acceleration than most,with 6-7000 lbs trailer that is.E70 35D is Ok handling wise,but mine rally suffers from the lack of a SLS.Brakes are good and I can climb very steep hills with 65 mph,5th gear @1600 rpm.Getting 18-19 mpg towing doesnt hurt either.My guess is that 35i wont be far off that numbers either.
If only E53 diesel was available here .....;)


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I am sure the 35d tows well. OTOH the 35i has a BMW performance chip available with BMW warranty.

35i has lower fuel economy but to recover the higher purchase cost of the diesel can take up to 80,000 km/50,000 miles for some of us, given diesel fuel prices. The diesel that makes sense for mileage is the 20d, not the 35d, IMO.

We'll see how the trend goes,but now the diesel is 40 cents per gallon cheaper than the premium gas,which is measly 91 here in California(which in turn means that the full potential of N55 cannot be extracted even with a performance tuning).

My only suggestion is if you get a diesel and have not driven/used one before read up and learn the differences otherwise youll run into issues. I tow around 8k with my 06 4.4i and have not had any major issues, just take appropriate precautions and keep up to date on maintenance. Diesel in my opinion is the way to go, but like i said get used to the differences ive seen tons of people come in with issues because the customer failed to understand the differences in the technology and operation

A diesel will ALWAYS be better for towing. Anyone who says otherwise is ignorant. The low end of the diesel and massive torque coupled with the better mpg while towing make gas engines look obsolete.


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That is an ignorant statement, IMO.

Low end torque is good for towing. A turbocharged direct injection gasoline engine has good low end torque as well. Torque peak on the 35i obviously isn't as high as the 35d, but it comes in at a lower rpm on the models I checked. And the torque band is much wider, meaning less shifting.

The peak torque number that matters is at the wheels, also known as rim pull. Engine torque is a good starting point, but that is why we have transmissions, to create rim pull. Flywheel torque is good for winning magazine comparisons though.

High diesel mpg is a good starting point, but an economic analysis will include the local cost of diesel fuel, and the higher purchase price of the diesel. I can make the economics work based on my local fuel prices, but given that the breakeven point is around 80,000 km without even considering the time value of money, it isn't a very attractive investment, towing or not.

Finally, diesels typically have little retarding capability unless they are fitted with an exhaust brake or similar retarding device. Basic science, and very important for towing any significant weight. Not sure how the latest BMW diesel performs here (I haven't towed with one) but it is a point to check on if you live near hilly areas (and if you don't, why would torque matter so much?).

I think port injected naturally aspirated engines look obsolete. The use of the Otto cycle vs the Diesel cycle doesn't dictate which one has direct injection and turbochargers these days.

Well that is your opinion ,Sorry but that is a complete load of piffle , a turbo diesel will shit over a petrol, you obviously havent driven one. Diesels also have a better retardation due to the higher compresssion ratio. There is no way I would contemplate towing with a petrol unless I was towing a fuel tanker behind me.

I didn't want to get into this, so I'll just subscribe...

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Diesel will not always get better mileage, it doesnt do well in stop and go driving. Also you have to look at other factors, diesel is a much thicker fuel and is less refined, which causes it to freeze quicker, but with modern tech thats not as big a deal. One thing is for sure, if you fail to upkeep, use injector cleaner, replace the filter then be ready to replace injectors constantly. The new emission regulations have taken a toll on diesels the DPF restricts the engines ability to breathe and causes many issues if not taken care of and used properlly. If you have not driven or are used to diesel then save yourself the hassle and learn the differences before jumping in, diesel engines are also compression based and require proper warm up and a good quality fuel for proper operation. Diesels are great, they last and are powerful but you better know how to drive it.

Now that was ugly.Diesel is using almost no fuel at idle,so it is very efficient,at long stops and at stop-go traffic.I am fairly agressive driver,but with a good restraint I can do 22-23 Mpg mixed driving in the LA traffic.I dont think that is achievable with any of the gas engines available,or with any low-mid size SUV this side of Honda CRV.