Torn between a 640i and 640D

[briansy]

Hi there, I am currently going through autotrader and scanning for top BMW 6 series cars with less than 50K miles and immaculate interiors.

I have found a mediterranean blue 640i with 46k, the right interior colour for me (ivory white and dark brown wood tone) and great condition.

And a carbon black with only 18K miles on it but interior is kinda uninspiring in black leather and black and silvery colour.

The black is in absolutely immaculate shape inside and out. The blue needs a tiny bit of a clean inside. The 640D black felt super quick off the blocks and the 640i just didn't but I only got to test drive it in 30mph zones near Clapham in London.

The blue has amazing looks and the colour combo is perfect. It also has 19 inch tyres with run flats which seem like it would drive nicer than the 20 inch on the black.

Forget price for now cos I will negotiate the petrol down - which would you go for? Have you tried both petrol and diesel version and what are your thoughts? I live in London and although I do like to get out of town on longer drives most of my drives are like 1-5 miles and no commuting.

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If you swapped the specs and miles and engine and put it on to the colour combo of the blue, I would go for it hands down. But I think I could be waiting forever to find a Diesel with all that in blue and cream. There is one I saw earlier today but interior isn't clean enough for me.

Thoughts?

[interstellar]

Your links don’t work but what makes you think you will negotiate the petrol down? It’s a sellers market so unless they have had it a while you might not get money off.

I had a 640i black with ivory , great combo and great car. I didn’t want the diesel as basically it’s a diesel and not a fan so not driven one.

The 3.0 petrol I thought suited the car. It was quick,smooth and a great long distance drive.

[briansy]

Yeah the Diesel feels a fair bit punchier and more torquey and you can barely hear the engine driving it. Hence why I'm torn. I think I can negotiate the price down as it is a very high price for those miles and there is less demand on the petrol given fuel economy and the 640D is so refined and punchy - it is also a private sale and the owner has had it on autotrader for weeks now. Who knows.

The petrol has 19 inch wheels which will help with refinement and ride (although they are run flats). But wheels still look good.

Maybe I need to test drive a 640i in an area where I can properly get some speed up. I also did the 640i test drive with owner in the car which put me off . Links again below in case these work

https://www.autotrader.co.uk/car-details/202202122...

https://www.autotrader.co.uk/car-details/202201311...

[BlueJ]

A vote for the petrol engine. I think diesel has had it's day, petrol engine a lot smoother, quieter, more satisfying to rev out when the opportunity arises, and no DPF issues. And in this case the petrol car looks WAY nicer, better interior.

Your journeys are mainly v. short, again better suited to a petrol engine (I think they warm up more quickly??).

I've had a couple of 3 litre single & twin turbo D's, they are lovely are torquey but beyond that not very involving.

[briansy]

Thanks Bluej. Has anyone specifically driven both the 640i and 640D?

[Maxus]

For short journeys in town I would definitely seek out a petrol. You would no doubt end up with EGR problems on the diesel.

I've got the diesel which is great for what I do, minimum of 10 mile trips but most are longer including a weekly 120 mile round trip to the office. Lots of torque, 43mpg and I quite like the sound it makes inside.

[briansy]

Maxus said:

For short journeys in town I would definitely seek out a petrol. You would no doubt end up with EGR problems on the diesel.

I've got the diesel which is great for what I do, minimum of 10 mile trips but most are longer including a weekly 120 mile round trip to the office. Lots of torque, 43mpg and I quite like the sound it makes inside.

Hi Max, would one longish run a week (or every fortnight even) of say 70 odd miles do the trick to sort this problem out?

[Maxus]

briansy said:

Hi Max, would one longish run a week (or every fortnight even) of say 70 odd miles do the trick to sort this problem out?

Maybe! It's the DPF that needs to go into its regen mode as well as potential EGR issues. DPF regen happens when the car is warmed and running at a higher speed for a period of time (the suggested variables are over 40mph for 15 mins). If you do this once a week or so it should be OK.

However, using a big diesel engine for mainly short urban trips is not ideal. I'd be searching out a petrol, particularly with the fuel price variance now.

[gobshite]

Hi pal

Get onto the Uk Facebook group, loads of info on there,

I have a 640d, I love it, done 30k so far in it,

Oil change every 8k, had the odd electrical niggle

Changed the run flats to PS4 which improved the ride, now has bilstine suspension which again has improved the ride.

Short journeys 30mpg, I have BimmerLink which shows transmission temp as well oil, realistically takes 10 min to get up to temperature.

I changed / upgraded to a Wagner intercooler and had a bespoke map, was at 286bhp 474lbf on the dyno before ended up 386hp and 575lbf

This was very much a conservative map.

Will do 49 to 51mpg at 70mph on a motorway run, my mixed average of 30k is 42mpg with the lowest at 19mpg.

Reversing camera is a must

A lot of car for the money

It’s also pretty massive

Kind regards

Angelo

[briansy]

So...if my research is correct, Diesel gives more torque at lower speeds, Petrol better torque at higher speeds and so Diesel quicker off the mark to about 30 MPH but petrol is beating the diesel from 30-70?

Could an engine remapping improve the torque at lower speeds in the petrol so it has that oomph of the Diesel whilst retaining the kick at higher speeds? Is this advisable?

[gobshite]

You will always get gains on a turbo engine

Derv will have a higher torque figure, pertrol will have a higher bhp for the equivalent engine size etc

I would always do supporting mods and increase the frequency of oil changes if your mapping a car. I would also recommend a live map rather than a flash

Unicorn motorsports will show you gains on there web page, there are plenty of reputable mappers out there.

Your going to be traction limited, I have kept my torque capped in the first 3 gears, if it’s wet it driven in comfort or eco, in sport it breaks traction

It’s fine in the dry.

Mine is quick from 20 mph upwards, in gear for overtaking, it’s surprising quick, but it’s a large heavy vehicle and you feel it when pressing on.

I would love the sound a petrol, but I’m an idiot so it would have an intake and exhaust

Will be taking min down the 1/4 mile at some point, I’m sure there will be results on the web to campoare the speed of both engines cars.

It’s not a sports car

[gobshite]

[gobshite]

[gobshite]

As you can see, there is a bit of varrience in the power,

I ended up changing lots of little bits, realistically the petrol has a higher bhp potential for the same outlay

I need the derv varrient for the overall economy of doing 25k per year.

Kind regards

Angelo

[MrCD]

briansy said:

So...if my research is correct, Diesel gives more torque at lower speeds, Petrol better torque at higher speeds and so Diesel quicker off the mark to about 30 MPH but petrol is beating the diesel from 30-70?

Surely the petrol is the better choice for day to day driving and rolling performance. How often do you need to go flat out from 0?

Likely you can get a remap to offer more torque lower down but I'd be inclined to leave as BMW intended. Is the 640d xdrive and the 640i rwd? That may explain the difference in torque mapping too. May just compromise traction off the line if chucking more torque at a rwd.

[gobshite]

briansy said:

So...if my research is correct, Diesel gives more torque at lower speeds, Petrol better torque at higher speeds and so Diesel quicker off the mark to about 30 MPH but petrol is beating the diesel from 30-70?

Could an engine remapping improve the torque at lower speeds in the petrol so it has that oomph of the Diesel whilst retaining the kick at higher speeds? Is this advisable?

I think the petrol would only pull past around a 100,

The petrol car had the better option, comfort seat are lovely

[gobshite]

MrCD said:

briansy said:

So...if my research is correct, Diesel gives more torque at lower speeds, Petrol better torque at higher speeds and so Diesel quicker off the mark to about 30 MPH but petrol is beating the diesel from 30-70?

Surely the petrol is the better choice for day to day driving and rolling performance. How often do you need to go flat out from 0?

Likely you can get a remap to offer more torque lower down but I'd be inclined to leave as BMW intended. Is the 640d xdrive and the 640i rwd? That may explain the difference in torque mapping too. May just compromise traction off the line if chucking more torque at a rwd.

No xdrive for the Uk unfortunately

I ended up modifying mine as I was board during lockdown, 😁

[MrCD]

Ah OK. That's a shame. I asked knowing the 4 series performance diesels came with xdrive so assumed that the 6 would too.

[dhibbert]

Hold out for what you want.

I bought my 640d in Feb last year, Deep Sea Blue with exclusive ivory nappa leather, full BMW history etc.

The options were important for me, had to have Professional Hi-Fi (677) and mine has variable damper control, 20" alloys, 360 cameras, rear camera, comfort access, comfort seats, sunroof, internet/apps, upgraded bluetooth/USB interface, leather dashboard, DAB radio, soft close doors, ceramic controls blah blah blah.

I like it, goes well and looks decent as well. What i found is that the dealers on AT add all the options to the advert as that bumps the 'price indicator' up. Even when I did VIN spec checks which clearly showed they didn't have the options they could care less.

[briansy]

Well, based on advice about possible complications with the Diesel down the line I went for the petrol. It has all the options I wanted although the seats are sports seats and not comfort but I think the difference is pretty marginal. I also wanted upgraded leather but the exclusive ivory nappa has these dark stripes which I didn't like at all so the Dakota ivory was fine. Head up display, 20 inch alloys, speed limit display, comfort doors, heated steering wheel and seats, reverse cameras, Harmon Kardon (which I think is bang average actually) and the dash and centre console had the dark wood look as opposed to silver so happy days really