MPG calculations 50i vs 35d

[DuSh]

So having exams every week is stressful and I need a break between studying, that's why I post often here some silly topics
This time my mind wondered what's the difference going by the fueleconomy.gov numbers for 35d and 50i - these engines are worlds apart in terms of MPG.......theoretically, and for some reason I thought difference should be astronomical. I mean come on now - a diesel sipping a fuel frugally and a heavy as fock high performance V8 monster drinking fuel in quarts every minute lol

Well results surprised me. Average MPG for 35d is 26mpg (city/highway) and for 50i it's 17mpg (city/highway). I drive around 12000 miles a year. So given a gallon price of roughly $2.6 - same price for 91 or diesel where I live (give or take of course depending where you live, in my city 91 and diesel cost same and there's no 93 here) difference comes to about $660 a year or $55 bucks per month Ooooooookay - well I was expecting like a $4-5k difference a year you know, considering all the specs, but $55 bucks per month?
I do understand those who drive more will have a bit bigger impact, and of course lead foot will probably increase the gap, but I'm still surprised to be honest. I wasn't expecting this low of a difference
Now I want to apologize saying that, because I know there are people for whom $55 per month is still money, but on the other hand I don't think there are many of such owners driving x5 f15 for whom $55 is a deal breaker - I mean it's a luxury premium SAV - let's be honest here

I'm shocked. Maybe it's too late and my mind is not working right and I made a mistake - please do correct me then

Maybe x5 been heavy (in terms of weight) SAV plays in favor of a more capable V8 that works under less load and maybe that's why difference comes not as much as i expected? I'm not sure what to think

P.S. all calculations are rough and numbers can be off - it was done just for very rough estimate - to see a big picture so to speak

P.P.S. Needless to say that difference between 35i and 50i per month/year will be even less! It's like $29 per month difference in fuel cost!

[TallTrees]

Unlike gas eco numbers posted on vehicles diesels regularly beat their advertised eco numbers in everyday use. I read an article on this a while back and it explained that it had to do with how the tests are setup by the Gov and how the manufactures try to get the best results with their gas engines(hwy fudge factor). I found this to be true for both my x5 35d and my wifes GLK 250d. Just my 2 cents

[deutsch100]

I am getting anywhere from 30-35mpg, sometimes a solid 37-38 mpg on my 2017 35d.

Between fills ups, I usually travel 500-600 miles on ONE tank of diesel.

I love, love the 50i, but I do not love going to the petrol station, so diesel fits my needs perfectly. LOADS of massive torque and infrequent fill ups. Win, win for me.

And since we currently own a G63 and M6...we get to spend plenty of time re-fueling!!! LOL

[Mr.47]

The X5 35d beats in economy, for gallons to gallons, your going to go thru more gas per month in a 50i then a 35d, which is going to cost you more regardless of Price per gallon.

Also you need to take account that In winters diesels are more expansive than summer blend usually summer diesel may dip as low as regular (87) gas, as premium gas will always be $0.50-$0.60 higher than regular.

And the with a chip in the 35d you can get up neck to neck in performance with 50i and with the benefits of efficiency, up to +305 hp and +500 lb/ft with some chiptunes. ok your not going to beat a 50i but you can get as close to one!

So for best of both worlds diesel is the way to go.

[ijaz429]

This was a properly done and thorough comparison. Other than the point made about manufacturer fudging #s, I think it is absolutely fair to assume the difference you calculated is accurate. Thank you for doing this.

[Gilly1964]

Originally Posted by ijaz429

This was a properly done and thorough comparison. Other than the point made about manufacturer fudging #s, I think it is absolutely fair to assume the difference you calculated is accurate. Thank you for doing this.

You're right! An interesting comparison, on paper.

But what does empirical evidence say?

I'll start. 30d (in the UK, so 35d to you guys and about 10% more on the mpg) and my lifetime average over just over 70k miles is 34.2 mpg.

[ijaz429]

Originally Posted by Gilly1964

You're right! An interesting comparison, on paper.

But what does empirical evidence say?

I'll start. 30d (in the UK, so 35d to you guys and about 10% more on the mpg) and my lifetime average over just over 70k miles is 34.2 mpg.

Yes but you would likely beat the tested ratings for an x50i as well based on your driving habits. For example, you are 8 mpg over the hwy diesel rating so you would also be over the hwy rating for the x50i if you drove the exact same routes in the exact same manner.

[Gilly1964]

Originally Posted by ijaz429

Yes but you would likely beat the tested ratings for an x50i as well based on your driving habits. For example, you are 8 mpg over the hwy diesel rating so you would also be over the hwy rating for the x50i if you drove the exact same routes in the exact same manner.

So let's all post our real-world numbers and they should average out the grandpas versus the boy-racers, no?

[ijaz429]

Originally Posted by Gilly1964

So let's all post our real-world numbers and they should average out the grandpas versus the boy-racers, no?

Although that would be interesting, the OP was talking about the difference between the 2 mpgs. To truly compare, we would have to take the same driver on the same route in both cars and then subtract one from the other. I'll half trust the manfucturers rated figures when just comparing against each other.

[Whazzup@NJ]

I did a similar calculation to the OP only I used a spreadsheet to try different assumptions about mileage and price between the diesel and the 35i. What i found is that, based on my expected driving style, the diesel would save about $50 a month. Seeing as the lease is $35 a month more I went with the diesel. I know it seems a little neurotic or OCD. I just guess I wanted to rationalize the diesel.

[AndreyATC]

Originally Posted by ijaz429

Yes but you would likely beat the tested ratings for an x50i as well based on your driving habits. For example, you are 8 mpg over the hwy diesel rating so you would also be over the hwy rating for the x50i if you drove the exact same routes in the exact same manner.

There is no way you can squeeze extra 8mpg out of 50i and obviously it won't be your lifetime average thing
At best, you may get 3-4 with tail wing going downhill
On diesel it's much easier to exceed EPA rating
So yeah, you'd be close to twice as many fill ups with 50i

[Jlu88]

MPG numbers will vary greatly depending on driving style and location as we all know.

Though for someone who drives in a city like NYC for 90% of the time, the difference between the 35d, 50i and perhaps even an X5M wouldn't be too much apart.

[ijaz429]

Originally Posted by AndreyATC

There is no way you can squeeze extra 8mpg out of 50i and obviously it won't be your lifetime average thing
At best, you may get 3-4 with tail wing going downhill
On diesel it's much easier to exceed EPA rating
So yeah, you'd be close to twice as many fill ups with 50i

technically, you would only need to squeeze an extra 5 mpgs from the 50i for the comparison to work. its roughly a 30% increase both ways (30% of 26 mpg is about 8, 30% of 17 is about 5)

[deutsch100]

Originally Posted by Whazzup@NJ

I did a similar calculation to the OP only I used a spreadsheet to try different assumptions about mileage and price between the diesel and the 35i. What i found is that, based on my expected driving style, the diesel would save about $50 a month. Seeing as the lease is $35 a month more I went with the diesel. I know it seems a little neurotic or OCD. I just guess I wanted to rationalize the diesel.

I am on my 2nd X5 diesel and I have had 2 MBZ diesels. I LOVE diesel. Love the sound, the torque and I have always had better luck with diesel passenger cars....for some reason (I know it makes no sense), but they have no or less problems in terms of overall car issues. Really happy BMW is keeping the X5d for 2018, but BMWNA could not guarantee they will keep it for G05

[mynameisplayer]

Having owned a tuned 40D, and now a 50i the difference is about 4-5 L/100 (4mpg). 40D was av 12.5, 50i is av 17.5. All city/school run. Both cars only get to about 10 l/100 on hwy (steady 115 kph, family of 5). Buy the 50i

[NOVA99]

One thing that no one has mentioned is Fluid Efficiency or Cost of Fluids. When you look at fuel costs it is important to include DEF consumption as well in the total O&O costs. I have never owned a light duty diesel and understand the DEF is probably in the full maintenance coverage of the vehicle but I am not sure. Keep in mind the average price of DEF is $2.80/gallon in the US so it does need to be factored in at some point once it is not covered by the vehicle maintenance plan. Additionally oil changes in diesels are more costly as well. Things to consider with diesel.

[DuSh]

This is my recent trip from work to home. 11 miles within 16 minutes including some stop lights. Done in Eco mode with start/stop enabled. It's a city 2 miles, then highway 7 miles and then finally city 2 more miles - which makes this trip roughly 35%/65% city/highway ratio. There are around 4-5 stop lights along the way. I drove staying about 5mph above speed limit - which resulted in half the traffic passing me, but half going with same speed. This is probably an average relaxed driver style, normal calm driving scenario for an average Joe going one way to/from work (assuming he lives 11 miles from work)

As you can see 24.7 mpg is a better than expected value for a 5000+lbs SAV with 500hp. I used 91 fuel (no 93 here). I would imagine on longer highway trips - I can achieve better mpg. One more thing to mention is that driving this way like a normal driver wasn't fun - you basically can't feel if you are in BMW or Camry, but on the positive side it was very calming down experience, almost meditating lol

Now, I agree that this was done almost at midnight when there's less traffic and in the morning numbers will be lower, but start/stop does help with stop lights (tho I hate start/stop) and heavy stop-n-go. Just out of curiosity I'll reset trip computer and post numbers of morning rush-hour trip (same route)

[Gilly1964]

NOVA99 I'm not sure that these are going to be significant. A DEF refill costs about £17 every 11,000 miles and my CBS servicing wants an oil change (on average) every 19,000.

[TallTrees]

In Toronto where I live Diesel costs approx 30% less than premium. My X5 35d burns about 35-40% less fuel than my outgoing 07 MDX 3.7l gas(required premium). For me after all things considered the X5 is pretty much twice as good as the Acura was it comes to fuel eco. I fill every 2-3 weeks which is a really nice bonus I didn't factor before buying.

[deutsch100]

Originally Posted by TallTrees

In Toronto where I live Diesel costs approx 30% less than premium. My X5 35d burns about 35-40% less fuel than my outgoing 07 MDX 3.7l gas(required premium). For me after all things considered the X5 is pretty much twice as good as the Acura was it comes to fuel eco. I fill every 2-3 weeks which is a really nice bonus I didn't factor before buying.

Yes...going to the Filling Station 1-2 times a month with my 35d, opposed to 1-2 times a week when I had my G550 or Full Size Range Rover is such a nice bonus. Refueling is one of those things I hate, hate to do. Not hard of course, but it just pushes my buttons

[Jlu88]

Originally Posted by DuSh

This is my recent trip from work to home. 11 miles within 16 minutes including some stop lights. Done in Eco mode with start/stop enabled. It's a city 2 miles, then highway 7 miles and then finally city 2 more miles - which makes this trip roughly 35%/65% city/highway ratio. There are around 4-5 stop lights along the way. I drove staying about 5mph above speed limit - which resulted in half the traffic passing me, but half going with same speed. This is probably an average relaxed driver style, normal calm driving scenario for an average Joe going one way to/from work (assuming he lives 11 miles from work)

As you can see 24.7 mpg is a better than expected value for a 5000+lbs SAV with 500hp. I used 91 fuel (no 93 here). I would imagine on longer highway trips - I can achieve better mpg. One more thing to mention is that driving this way like a normal driver wasn't fun - you basically can't feel if you are in BMW or Camry, but on the positive side it was very calming down experience, almost meditating lol

Now, I agree that this was done almost at midnight when there's less traffic and in the morning numbers will be lower, but start/stop does help with stop lights (tho I hate start/stop) and heavy stop-n-go. Just out of curiosity I'll reset trip computer and post numbers of morning rush-hour trip (same route)

Nice numbers! How was the elevation? I don't think I can do much better than that in my 35i

[Van1]

Originally Posted by NOVA99

One thing that no one has mentioned is Fluid Efficiency or Cost of Fluids. When you look at fuel costs it is important to include DEF consumption as well in the total O&O costs. I have never owned a light duty diesel and understand the DEF is probably in the full maintenance coverage of the vehicle but I am not sure. Keep in mind the average price of DEF is $2.80/gallon in the US so it does need to be factored in at some point once it is not covered by the vehicle maintenance plan. Additionally oil changes in diesels are more costly as well. Things to consider with diesel.

How much is an oil change in a 35d vs a 50i? Haven't paid for an oil change yet in my 35d so I don't know that answer. Having changed the oil myself in my previous VW Touareg V10 TDI the only thing that made it more expensive than say a gas V6 or V8 Touareg was the fact that it took 12 quarts of oil. But the VW 507 spec oil is no more expensive than the VW 505 spec oil I buy for my VW R32 and oil filters are about the same.

Lots of variables being mentioned in this thread in comparing the operating cost of the 35d vs the 50i but the one big thing that is missing from the discussion is the initial entry price between the two. The base price of the 50i is $13,000 more than the 35d.