Z4-forum.com

I’ve decided not to go for a E85 and instead look for a E89.
What is the best engine size to get in terms of fuel consumption?

Although I don’t have one if fuel economy is your issue then a 23i manual is your best choice..IMHO..

23i if you want a 6 cylinder but an 18i if you take the 4 pot but my 23i will do over 40mpg on a run

If you are considering the 23i then it would be wise to take a look at the 30i, in the real world it will do almost exactly the same MPG but with more power and rarity which will help future values, sounds better too. My 30i gives me early to mid 40s MPG on a long run and around town around 22 to 24 MPG. The 4 pots might offer you a bit more economy but probably not by much.

IMHO, the best E89 in terms of petrol consumption is the Prius.

I don't want to discourage you, or turn you away from your dream car. But if you're concerned about your petrol budget, an E89 is going to be very disappointing. And maintenance. Mind the truism: Bring More Wallet.

Good luck!

what is fuel consumption?

Marcoose wrote: ↑Thu Jul 22, 2021 12:14 am IMHO, the best E89 in terms of petrol consumption is the Prius.

and true.

My daily drive in a 23i is 7 miles to work, so temp. just start to rise half way into journey.
3 miles urban with 3 stops at traffic lights, the rest country lanes.
Careful driving i can get 33, usually 30mpg.
Motorway i can get it up to 45mpg.
But at the time i bought i was not aware of the 30i, but probably back then out of my price range like 35i's..
Also more colour and options wise when looking for 23i.

tintoverano wrote: ↑Thu Jul 22, 2021 5:12 am what is fuel consumption?

I think its how much food you eat while driving. MPS = Miles Per Sandwich.

If you want good economy, you're looking at the wrong cars and you probably won't enjoy ownership because you'll constantly be holding back with one eye on the trip computer. SLK/SLC diesel might be worth looking at?

My 30i did about 31mpg over 10,000 miles and the 35is is regularly taking me to the petrol station.

If you are set on an e89 then the 23i is the way to go, yes low to mid 30's round town and mid 40's on a run but you have to pay somewhere for the looks / style of the car.

Not sure I would be worried about £300 a year in fuel over an SLK diesel.

30i is a great engine but cost a lump more to buy initially - what is the budget, required spec etc?

23i with a long running average of 34.8 MPG here.

Any fuel consumption figures you get or recommendations are only going to provide you will a very rough and general guide.

The fuel consumption on a Z4, and any other car, I’d going to be dictated by how YOU drive it.

I’ve had a 23i, a 35iS and now an M40i

The 23i was great on a run taking it very easy but when I went up my local twisties and gave it plenty the mpg dropped down mid teens, average low 20’s because you had to rev it a lot more to get the best out of it in a fun sense.

The 35iS on the motorway with cruise on was very frugal and returned nearly 40 mpg on the 500 mile trip home. When I got it home the average was 25/26 mpg and if you were out for a fun day would could drop to low teens (which Will (Tiglon) the new owner is attesting too) but that was rare to be that low, mid 20’s was the norm.

The M40i is the most economic out the lot so far, as it’s not run in yet and hasn’t been getting much spirited driving. It’s returning an average of 34.5 mpg. This will most definitely change when it’s got a few more miles under its belt but I do feel in normal driving with the 8 speed box it can be pretty frugal if it wants to be, and the driver will let it be.

As said the 23i and 30i are very similar and if you can stretch to the 30i go for it.

I have no experience on the 4 cylinder turbo engine but as usual with anything with a turbo, the more you spin it up, the more fuel it’ll burn.

Echoing other’s sentiments, I hope you do buy one as they’re great cars, stunning looking and don’t look anywhere as old or relatively cheap for what the are, but…………… if fuel consumption is one of your main considerations then it may not be the car for you. I think when you own a car like this you just accept that it will need filled up reasonably regularly and it’s just a cost of ownership

I'm assuming from all the comments that you're being steered towards a 6-cylinder model?

Just for balance I have a 20iS, manual gearbox, remapped to 279bhp. In normal daily use, which is usually a 28 mile each way commute down twisty B-roads, it returns 36.6mpg.
Recently took it to the Lake District from Norfolk, A11, A14, M6, between 70 and 80 all the way there and back and it showed 48.2mpg.
These figures are as shown by the trip computer, not calculated by me. I reset it at every refill.
Interestingly, before the remap, my commuting figure was down around 32mpg, so I can only assume the extra torque is beneficial.

I should admit though, that after a spirited drive home from work one day it did drop to 30mpg, but that was really giving it some stick trying to hang on to the back of an Elise! (Which must have been driven by a numpty as I did manage to stick with it)

Personal experiences will vary, but using bmw’s own figures show the 2litre turbo cars to be the most economical & cheapest to tax
Rob

Not sure why people are so hard on this question, it's not like we've not had it before and imho there is absolutely nothing wrong with wanting the most economical version of a car you desire, doesn't mean they cant afford to run it just that they're running it with their head as much as their heart, personally the less i can give to the government in fuel duty, road tax and associated vat the better.. not like we dont pay enough already is it?