335i Questions

[msportpanda]

I’ve just picked up a 335i as a daily and mildly regretting the decision so far.

It’s a great car, comfy, good looking but I am a bit shocked at the motorway mpg.

I’ve only managed 27mpg on cruise at 70mph for 50 miles of almost 90% motorway driving. Can any owners indicate if this is about right or if mines a bit fubared?

I bought it to replace my z4m as a daily driver and the Z4M will do a solid 30-32 on the same journey with no cruise control.

I know it doesn’t sound like a huge difference but just would’ve expected a bit more out of it.

The only thing I can think is that it’s running an MHD stage 2+ tune but that said I was only cruising and not getting into the boost at all

[aaron_2000]

Doesn't sound right. We ran a 340i that could get over 40mpg on a run

[wax lyrical]

my 2008 335i auto can do 32 mpg at a steady 75/80 mph, so the engine mod might be having an impact on yours.

[ro250]

Agreed, that's not right. Our 440i gets 40mpg on a motorways run without trying hard. What you describe is more like what I get round town/combined.

[Court_S]

What age is you 335i?

I've just bought an older one and it seems pretty easy to nudge it over 30mpg without really trying especially cruising at 75.

[msportpanda]

It’s a 2007 car with 105k miles on the clock. I knew it wasn’t going to be amazing being the old N54 but I would’ve thought early 30s on a 70mph cruise would be doable!

Will try to flash it back to a stock map and see what the difference is.

[msportpanda]

I reset the lambda adaptations last night on the car and it runs absolutely fantastic now, fuel economy is sensible and there's a boatload more power from it now!

So, I'm just trying to understand what I need to sort out to stop the car from returning to it's odd overfuelling state...

[wax lyrical]

My car is stock and I tested it at a steady 75mph on the M25 yesterday. Got 37mpg. That's on Shell V-Power.

[MarkosGTV]

Are you going off the display or working out the MPG the old school way? I very rarely got 30+mpg out of my Z4M Coupe over the 5 years I had it, although I normally cruised over 70mph in that to be fair. 30-32mpg is very good going in that I think. N55 will get high 30's on a 70mph cruise but no experience with the N54, but would think it would be mid 30's perhaps.

[wax lyrical]

That 37 mpg is going off the trip computer. Is that not accurate?

MarkosGTV said:

Are you going off the display or working out the MPG the old school way? I very rarely got 30+mpg out of my Z4M Coupe over the 5 years I had it, although I normally cruised over 70mph in that to be fair. 30-32mpg is very good going in that I think. N55 will get high 30's on a 70mph cruise but no experience with the N54, but would think it would be mid 30's perhaps.

[MarkosGTV]

wax lyrical said:

That 37 mpg is going off the trip computer. Is that not accurate?

That can be a couple of MPG out, normally over-estimating.

[Court_S]

msportpanda said:

It’s a 2007 car with 105k miles on the clock. I knew it wasn’t going to be amazing being the old N54 but I would’ve thought early 30s on a 70mph cruise would be doable!

Will try to flash it back to a stock map and see what the difference is.

Same engine as in my car then.

I’ve been impressed with the frugality of it so far in day to day pottering. Mine is on the stock map.

[ro250]

MarkosGTV said:

wax lyrical said:

That 37 mpg is going off the trip computer. Is that not accurate?

That can be a couple of MPG out, normally over-estimating.

But as that's how most people measure MPG, it's all relative

Maybe ignore my MPG comment above as mine's a B58 engine.