This week I decided to run my motor brim to brim until it said 0 miles to refuelling on the maxidot. Coincidentally this happened to be 700 miles exactly when I filled up. I put in 63.4 litres of derv which I calculate as almost exactly 50mpg. Most of that mileage was done on M6/M42/M40/M25 this week at a comfortable speed but not exceeding 70mph. Now, for an old style 2.5 V6 TDi cruiser I think that's pretty impressive.

To answer the question.... about 330 miles.

Not enough? Well, it's 330 miles in under 2 hours 30mins. This is why I like my 2.5TDI

Plus if you remove vent valve in the tank filler neck, the full tank capacity is actually 69l (15gal), which enough to cross Germany in under 3hrs if you drive fast, or do 750miles if you drive slow.

By the way, a couple days ago, out of boredom, I recoded my instrument cluster from UK (31415) to EU (31115). This gives you l/100km reading instead of mpg, plus one unexpected benefit: when the car is stationary, maxidot shows idle fuel consumption in litres/hr. And this is where it gets interesting:

Engine warmed up and idling, everything else off, fuel consumption: 0.6l/h (0.5 popped up on display for a few moments).

Cd/sound system on, DRLs on, heated seats on and set to '1': 0.7l/h, not much difference

Airco on: 1.0l/h for as long as the compressor is turning, does not matter if it's hot or cold (interior temp 19deg, outside temp 10deg C).

So, the bottom line is this: if you like the interior air conditioned, it makes little difference if you have 1.9, 2.0 or 2.5tdi

By the way, the display is quite accurate on my Superb (quite unlike my 1.9TDI Octavia).

I tested recently on a 450 mile drive (also across Germany), at constant speed of 105mph, cluster showed 31.5mpg, distance/fuel worked out at 31mpg.

Edit: All speeds as measured by GPS (speedo overreads 6-8mph above 100mph)

Edited 13 March, 201115 yr by dieselV6

Interesting, I too find the maxidot fuel consumption display to be spot on when compared to a brim to brim fill for comparison.

My PD 130 1,9 goes about 800 miles on the tank. It's vent modded and it's 85% freeway 70+mph driven. It goes about 1000 miles @ tank, if i drive around 55mph.

Oh and the engine is professionally chipped (no box) to 165bhp @ 380nm.

So, it is 800m at UK motorway speeds, vs 750m of the 2.5TDI at same conditions.

The 50mph/1400rpm fuel economy is also ridiculous on the 2.5TDI- though I have never been patient enough to try it out.

Just proves the point that in real-life conditions (airco on) there's not much difference in consumption.

I trump your 165bhp with another +30bhp on top (195bhp+)

Impressive figures though for an old barge like a Mk1 Superb either way. Long may it roll on.

I am interested in this vent mod too! I did once make it from Austria to Luxembourg on one tank, but that was taking it easy, sub 75mph. Gunning it at 100-120 all the way I get around 37mpg on mine. So yea, I agree, the 2.5 tdi is really made for this kind of work.

I can only squeeze in 54 litres when running on vapours, I really wish I could put in 69 litres, so please explain this vent mod!!

I am interested in this vent mod too! I did once make it from Austria to Luxembourg on one tank, but that was taking it easy, sub 75mph. Gunning it at 100-120 all the way I get around 37mpg on mine. So yea, I agree, the 2.5 tdi is really made for this kind of work.

I can only squeeze in 54 litres when running on vapours, I really wish I could put in 69 litres, so please explain this vent mod!!

Page 183 of the manual, press the vent in (as it says not to do ) and it will fill the tank right to the top. In the Octy 1 manual it explained how to do it! I presume the vent mod just removes this valve?

I just use the edge of the fuel nozzle to press the valve whilst filling the last part of the tank.

Yes, you can remove the valve completely - need to undo screws holding fuel filler flap/cover, behind it there is access to the back of the valve, it is a push fit with latch. Fiddly job, though very simple.

On a diesel, removal of this valve is quite safe thanks to lack of vapour control and low thermal coefficient of expansion of diesel fuel. Never ever do it on petrol ones, petrol expands with temperature and can flood vapour control system (and leak out/catch fire etc).

Yes, you can remove the valve completely - need to undo screws holding fuel filler flap/cover, behind it there is access to the back of the valve, it is a push fit with latch. Fiddly job, though very simple.

On a diesel, removal of this valve is quite safe thanks to lack of vapour control and low thermal coefficient of expansion of diesel fuel. Never ever do it on petrol ones, petrol expands with temperature and can flood vapour control system (and leak out/catch fire etc).

Thanks for all this.

I just don't understand how the whole system works: does the valve by default not allow the fuel tank to be filled to max? It is just that I can see the fuel foaming when I brim it - so is there something like a spare chamber worth 14 litres of fuel or so that is otherwise empty and by removing the valve we also end up using this expansion chamber? I would be quite happy with 69 litres to be honest! Miss the 80 litre tank on my old Peugeot 605 diesel!

Thanks for all this.

I just don't understand how the whole system works: does the valve by default not allow the fuel tank to be filled to max? It is just that I can see the fuel foaming when I brim it - so is there something like a spare chamber worth 14 litres of fuel or so that is otherwise empty and by removing the valve we also end up using this expansion chamber? I would be quite happy with 69 litres to be honest! Miss the 80 litre tank on my old Peugeot 605 diesel!

Yes you are pretty spot on with your thoughts, if you don't fancy taking the valve out then it can be simply vented with the fuel pump nozzle, giving the same desired effect - just a little trickier to put the last 15 litres or so of fuel in.

It's only 6l to 7l extra space, not 15l I am afraid. Without pressing/removing the valve, you can get 62l-63l in, though you'd have to fill up really slowly to let the foam go out.

After removing the valve (or pressing it during fill-up) you get 69l when filled to the brim.

Mk1 Octavia for some reason had even bigger expansion space, the numbers there were 55l unvented, 64l vented, so 9l extra. When I was using it for travel across Europe, removing the valve made a huge difference.

Not many saloon cars out there with 80l fuel tanks anymore, and full size spare wheels are also on the way out. It seems that grand touring is out of fashion. I had my mind set on getting Audi A6 3.0TDI quattro because of the great engine for autobahn, 80l+ fuel tank (enough to cross Germany at high speed), and a full size spare. And guess what, latest A6 has 65l fuel tank and a toy spare. No thanks, I'll keep the Superb on the road for as long as possible.

It's only 6l to 7l extra space, not 15l I am afraid. Without pressing/removing the valve, you can get 62l-63l in, though you'd have to fill up really slowly to let the foam go out.

After removing the valve (or pressing it during fill-up) you get 69l when filled to the brim.

Mk1 Octavia for some reason had even bigger expansion space, the numbers there were 55l unvented, 64l vented, so 9l extra. When I was using it for travel across Europe, removing the valve made a huge difference.

Not many saloon cars out there with 80l fuel tanks anymore, and full size spare wheels are also on the way out. It seems that grand touring is out of fashion. I had my mind set on getting Audi A6 3.0TDI quattro because of the great engine for autobahn, 80l+ fuel tank (enough to cross Germany at high speed), and a full size spare. And guess what, latest A6 has 65l fuel tank and a toy spare. No thanks, I'll keep the Superb on the road for as long as possible.

I don't know why they keep reducing fuel tank size, must be a crash safety etc etc blah blah blah driven design step...

Even though diesel doesn't burn readily!

Yes, the 3.0 tdi is nice, but a lot more money than the Superb.

Is yours tuned then? I have had mine up at 110mph over extended periods of time between Regensburg and Nuremberg on the A4 in standard 155PS tune, took that quite happily :-) Going again over Easter :-)

Ever since Mk2 Superb dropped multi-link front suspension / longitudinal engine, there's not much choice for tall drivers with passengers in the VW land. Audi A4 (or Seat Exeo) is way too small, only A6, A7, A8 and VW Phaeton are about same legroom as Mk1 Superb and have longitudinal platform with decent high-speed suspension, plus enough bhp and range to match.

I spent 4 years travelling across Europe in the Octavia, and while it was very good for the money (especially after 5-speed to 6-speed box swap), frankly standard McPhersons are not precise nor comfortable enough above 100mph.

You can get lower priced A6 with smaller engines, it's just if I spend so much money, I might as well spend a bit more and get everything I want from a car. Of course, by removing full size spare and downsizing the fuel tank Audi has removed the problem and improved my cash flow immensely

Stock power (155bhp earlier AYM, 163bhp later BDG) is good enough for long cruises up to about 115mph actual (122 indicated).

You can up the power by chipping to about 190-200bhp on 2.5TDI, but it is best to replace precat with pipe (you still keep main catalyst). BDG engine precat is quite restrictive (actual numbers for MAF are 5%-7% higher around 4000rpm/full power if you decat the precat ) The 155bhp is older AYM engine, no precat on this one (and no problem).

The extra power allows to cruise at 130mph+ actual without undue stress (as in 150+ hours above 130mph so far and counting). Keep in mind fuel usage is 22-23mpg (12-13 l/100km, 300miles/tank) at these speeds.

Going higher with power does not make much sense as the car is pretty much gearing limited (~145mph at 4300rpm, this is not CR, lower injection pressure and so quite pushing diesel burn rate at these revs).

You can fit van tyres 195/65/16 to get extra 5% longer gearing (thinking about it), but for now there seems only one supplier that makes them in high speed version (V rated Bridgestone).

Interesting notes.

Is yours the BDG? I regret in a way not buying a 6 speed manual BDG instead of the 5 speed auto AYM. Much more tuning potential .

Although common rail is a lot more sensitive to fuel quality etc so AYM should be less costly in the long term if the VP44 doesn't give me too much trouble. Maybe I will swap for a BDG at some point.

I have looked at lots of cars and really for someone like me (6'4") with a family the Superb is a blessing. Not many cars around like it. I have considered the LWB S320cdi at the time and decided to go for the Superb as I preferred the interior.

For my family wagon, cruising very comfortably at 90-100mph is what the car does best in Europe. I have taken it higher, but no point, as you run out of fuel too quickly! Not in this country thoughm with these diesel prices plus all too many average speed cameras etc etc where the big brother is watching....

My old 57' plate Superb 1 (130 BHP TDi PD) emptied pretty much a full tank on a single run from south west Scotland to Lands End - 4 people in the car and a boot-full of luggage.

Funnily enough, 6ft5" here.

Fuel in the UK is approaching ridiculous - I'm off to Calais on Saturday and the ferry ticket will be mostly paid by filling up in France (20p/l difference!)

My European trips tend to be in 10hr-12hr driving time range - and then shortening the drive by 1hr-2hrs makes a lot of difference, more than the extra fuel/tyre cost (tyres go much quicker above 110mph).