Who has had the best/biggest fuel economy?

[jammy_basturd]

Almost following on from where Top Gear left off last night, who has had the best mpg from their Cerb? I know the Cerb isn't the car to drive if your worried about that kind of thing, and I doubt most of you even bother working out what mpg you get, but just wondering if anyone has sat in top gear rolling along at 50mph before to see how high they could get their mpg?

Anyone had more than 30mpg?

[eLSerbera]

I think this has been discussed briefly here before, with most people getting around(+/-3) the 20MPG mark,
Really with these engines getting 30 would need downhill all the way (and a tow on the way back up), pretty sure that with the technology used in the ignition/injection the mapping would still have fuel being injected with zero load (coasting) on the engine, aren't the ECU systems setup with batch injection?

In any case when people want pops and bangs from the exhaust you are not looking to minimise fuel burning inefficiency.

[jammy_basturd]

Yea, I'd been looking over old topics to see what most people were getting with general driving. Was thinking more along the lines of an 'out of the ordinary' situation, wondering if 40mpg was possible, and I'm not talking about on the back of an AA lorry!

[Brummmie]

250 miles to a tank, whatever that is?

[Dave 500]

Brummmie said:

250 miles to a tank, whatever that is?

Snap give or take a bit.....

[BCA]

31 mpg once, on the return trip from a trackday... Everything nice and warm with a lightly traffic'd motorway drive back at not too silly speed.

I believe the average of ours has also gone up to around 20ish mpg now since Trackcar remapped it, a nice little bonus alongside the extra power.

[Byker28i]

27mpg at 85mph cruise, nice and gentle on the motorway/toll road in 5th gear. Done it quite a few times as well so it wasn't a fluke.

[TheFarmer]

I often do a round trip of 1100 miles to visit my Father in the Lake District. Mostly motorway miles and average 27-28 mpg if we DO NOT GET stuck in traffic. The best I have seen from a tank is 305 miles before I stopped to fill up.

[jammy_basturd]

Well finally got to drive/pick up/own my dream car today. On the way home from my girlfriends I reckon I used about £12 @ £1.25 a litre over 70 odd miles. Not the most accurate calculation, but not bad. Was doing between 60-80 leptons, apart from a stint of heavy traffic on the M25 when I was down at about 20-30 leptons.

[optimax sniffer]

Got 350 miles from a tank on the way back from the 'ring trip last year, at that was at a 100 lepton cruise.

[julian64]

I think you want to ask yourself whether you would want to run the AJP leaner on a regular basis.

[Steve_T]

I have a switchable MBE map from Austec. One map is leaner for covering longer distances at a sustained cruising speed (trips to France) and the other is a regular map for better drivability around town and blatting around. Both maps are the same for the higher load sites so if you boot it the engine does not endure lean running under load.

Steve.

Edited by Steve_T on Wednesday 25th June 15:10

[optimax sniffer]

julian64 said:

I think you want to ask yourself whether you would want to run the AJP leaner on a regular basis.

It was down to about 6mpg at the ring though

[Mars]

julian64 said:

I think you want to ask yourself whether you would want to run the AJP leaner on a regular basis.

I'm sure Trackcar-Jools told me (possibly on a thread here) that the AJP runs near to stoic for max power. It'd be a useful experiment to install a wideband lambda iun the exhausts and do some logging. Better-still, the newer Emeralds have a self-mapping facility. I bet the part-throttle areas of the map could be cleaned up for better economy without sacrificing the "power" areas.


For example, my Caterham when delivered in 1999 has 190bhp and would manage about 180 miles from a full tank.

After the Emerald was installed and DW concentrated on the part-running areas of the map, it was up to 200bhp peak, a smoother curve all-round with incremental gains everywhere AND it would now manage 220 miles per tankful.

Even after very many upgrades where the engine increased in capacity (marginally) with both power and torque increased significantly, I was still getting substantially over 200 miles from a tankful.

About this time I started experimenting with the Emerald self-logging facility and a Perl script written by a friend to compare the logs against required AFR. The intention was to improve the map even more. I didn't get very far with it but the Emerald now has self-mapping as a built-in facility so this would be trivial for someone to do with the Cerb now. Well worth it (IMO) considering the general cost of running one.