New personal best MPG.

timmus

A2OC Donor
Hi folks,

I drove my car from Lancaster to Sarge's place in London to have him service my car. I then drove from there to Liverpool and then back to Lancaster. I averaged 71.2mpg over the entire trip. That's the first time I've cracked the 70 mark over the course of an entire tank of fuel, which makes me smile!
It was mostly motorway miles, of course, but I probably did a total of 30 miles of urban driving and traffic jams. Cruise was set to a true 60mph unless I was in average-speed sections of the M1.

I'm running the longer 5th, though I've only got 1/3rd of the underbody mods, so hopefully I can squeeze a little extra economy in the future. I also have 17" wheels, so they're clearly not too bad for economy when on a run.

Cheers,

Tom
 

a2sumo

A2OC donor
Good work Tom last summer vonnie and i drove from Essex to Birmingham to stay at Robins. We took both my fsi and Vonies tdi on the way up Vonnie averaged just over 70mpg ---- i put it down to clean air following my fsi lol
keep up the good work Mike
 

dan_b

A2OC Donor
Good stuff! My best tank is 67MPG average so far -determined to break the 70MPG barrier somehow!
 

DJ 190

A2OC Donor
If you have changed your wheel size, then does this affect your speedo reading AND you mileometer? I fine it hard to stay around 60 mpg , but I'm not going to lose any sleep about it!
 

timmus

A2OC Donor
Thanks Mike! You may love your FSI, but perhaps you and Vonnie would burn less fuel between you if you followed her in convoy! :p

David, my car is geared-up by my tyres. My speedo is bang-on and my trip odometer is about 4% under the true distance travelled.

Dan, you'll manage it when the opportunity presents itself. I've known for a while that my car was capable of doing a 70mpg+ tank because I've had 70 or more on shorter journeys, but getting 70+ from an entire tank required me to drive almost exclusively on motorways at a sensible speed with an up-to-temperature engine for almost every drop of fuel burnt.
Having thought about this feat a little more, I'm surprised to have achieved it in mid-winter! The average temperature on my journey was, I'd guess, about 7 degrees. Roll on summer and I'm sure to beat my personal best again! :)

Tom
 

bretti_kivi

Member
but somewhere in the high single-digit celsius is pretty much optimal.
- it's not so cold that the warmth is lost from the engine quickly
- cold air works better (intercooler!)
- it's cold enough that the intercooler can work really well
- it's cold enough that the tyres are quite hard
- there's no real need for climate, so it's off

... I would be surprised if you got significantly better in much warmer times. I think you'd probably increase the numbers by another 10% by slowing down 5%, i.e. to 66mph or so.

Bret
 

timmus

A2OC Donor
You're right, Bret; it's a double-edged sword. Colder air is denser, which means drag is increased, but I get a more oxygen-rich charge of air into the engine, along with the other benefits you've listed. I shall see what happens in Spring, but I'm only expecting an extra few mpg at best.

Tom
 

dan_b

A2OC Donor
I think Brett has hit the nail on the head with the temperature stuff. I've also seen an increase in MPG switching from my 195/50/16s (alloy) summers to to my narrower and lighter 155/65/15 winters (steel) - the combination of the narrower tyres, colder (but not too cold) temperatures, and slowing down a bit (60mph max) has seen my per-tank MPG rise by a good 6MPG for the last few fill-ups.
 

timmus

A2OC Donor
I'm in the (slow) process of sorting myself out with a set of narrow 15" winter wheels. I've got the alloys, but I'm unlikely to get any tyres until summer; I'm hoping I'll get a good deal on winter rubber when demand is low. No doubt I'll see an increase in mpg when running them, which will hopefully help to off-set the effects of the cold. However, I'm willing to pay a little to run 17" wheels most of the time. With FSDs and 45-section tyres, I find they're comfortable enough and I just love the look of the car. I'm clearly a victim of my own vanity!

Tom
 

dan_b

A2OC Donor
I agree the A2 looks great lowered and on 17s, but my back just can't cope with it anymore - I started on SE 16s then went up to summer 17s for a while, then changed to TT 16s, and now I will be running on summer forged 15s when it gets warmer - I'm clearly a victim of my own indecision!
 

timmus

A2OC Donor
My car's not lowered at all as I do too much driving on Lake District roads. In conjunction with my oversized tyres, perhaps that's why I find the ride on 17" wheels perfectly acceptable.
I have driven my car briefly on 15" wheels with 195/55 tyres and the ride was plush, so I do understand your decision, Dan.
 

DJ 190

A2OC Donor
Surely, there is no way that those 17" wheel/tyre combination can be Comfortable? The single biggest improvement to my driving "comfort" was changing to 15" wheels with 185/60 tyres! Forget those FSD's that I then fitted..... The improvement with the tyres was immediate! I thought that after the FSD's had been fitted, it was worse that before! (honestly!) I have a full Votex body kit just fitted, and, although I know how fabulous it would look with your wheels, I'm just not prepared to loose that much-improved ride quality! I might try plastic white wheel discs which are usually fitted to the "Campervan" They are trapped between the rim and tyre (sometimes it is advisable to fit inner-tubes) The effect could be good, and, of course, they can be simply removed if not! They are about £50 a set ..... could give a "low-profile tyre" effect? Anyway, I sure that my 15" wheels don't make people point in disgust! L.O.L.!
 

DJ 190

A2OC Donor
Hey, I've just had a "blinding" thought! How about a temporary wheel/tyre swap! You could experience my 15" wheel/tyres and I could see how my car looks/runs on 17's with 40 section tyres? Could be for as long or short a period as you wish. You have said that you were thinking about 15" wheels? If I came to see you again, I'd certainly be careful on the way back! L.O.L.! ( Maybe it would be better if I could show you MY hospitality, here in Beautiful North Wales!)
 

timmus

A2OC Donor
I have seen many an A2 with 15" wheels looking very attractive. I can't imagine anyone points in disgust.
I haven't said I was thinking about 15" wheels; I have a set awaiting the fitment of winter tyres, but my 17" wheels are here to stay!

As I say, I find my setup perfectly comfortable. To begin with I was underwhelmed by my FSDs, but as they loosened up and bedded in, I began to see the benefits and think they're great.
I changed to 205/45 tyres about 3 weeks before having the FSDs fitted, so was able to assess the impact of both changes. 17" wheels with standard tyres (40-section) and standard suspension wasn't acceptable, but the change of tyres made a huge difference, well beyond what I was expecting. I remember first driving around on them and being amazed by the extra bounce. FSDs without shorter springs also, in time, added noticable extra comfort.
Whilst I won't claim to have the cossetting ride offered by 15" wheels, I do think I've found a way of making 17" wheels comfortable.

Tom
 
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DJ 190

A2OC Donor
Yes, I realised that I made an error with that "40" section straight away .... You have got me thinking about 17" wheels .... I wonder what the change in "comfort factor" is between our two combinations? There is a Guy in Germany that listed this, but I'm not sure what the factor was for your wheel/tyre set-up? Now, if and when you fit anything else to your car, (and your other wheels are just stored), I wonder if I could try your 17" 's for a short period. Wear would be minimal and I would compensate you, anyway? It would just be an opportunity to see how they ride, without the big expenditure!
 
Interesting.. I swapped to 15" pepper pots with 185/60 Alpin4 winters back at the end of November from RS4 16" replicas with 205/45 Continentals expecting a much more supple ride. While there was a difference, however it was fairly minimal. I had always thought the the ride on the 205/45/16's to be pretty good (I also have Koni/FSD's fitted with SE rear springs). Maybe there is more to the step up in aspect from 40 to 45 than the numbers suggest?

One thing I will add is my MPG has decreased (subjectively) since I fitted the pepper pots and winter tyres. I haven't had a chance to do a direct comparison yet and i'm still playing with the tyre pressures.
 

MikeMarsUK

A2OC Donor
...
One thing I will add is my MPG has decreased (subjectively) since I fitted the pepper pots and winter tyres. I haven't had a chance to do a direct comparison yet and i'm still playing with the tyre pressures.
Most likely simply due to the lower MPG everyone gets in winter (it takes much longer for the engine to warm up). My MPG has crashed to the floor in the last couple of months. All else being the same you'd normally expect to see a (modest) improvement in MPG when going to narrower tyres with a higher profile.

Were the original tyres LRRs?
 

timmus

A2OC Donor
Well folks, I've broken my personal best again: 72.1mpg over a full tank. This time it was Lancaster -> Cambridge -> Lancaster.
I did both journeys late into the evening so met no traffic whatsoever. I didn't stop once in either direction, and the car wasn't used at all whilst in Cambridge. Cruise was again set to a true 60mph. I can't see myself beating this figure without adding the final aero mods. The only way I'm going to get better economy figures is to either slow down, or change my 17" 7J alloys.

Tom
 

MikeMarsUK

A2OC Donor
Congrats :)


The 17s will be having an impact, but it's hard to say how much exactly. You can do better than the cruise control - let the speed drop slightly as you are going uphill, and let it increase (or freewheel) down the hill. The CC will be trying to hold the speed rigid, and that isn't optimal. Having said that, the mpg difference will be small.
 
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