Most expensive fuel stop?

[cyberface]

Here's a challenge for you all. I recently had to go to a wedding in Farnham with my girlfriend (it was one of her work colleagues getting married - I didn't know anyone there and wasn't really in the mood for it, frankly), but to make up for it, I took the cross-country route back home to Kent, through Hazlemere and back via the A264. It was a sunny dry day and a great drive. However, I ran the tank down dangerously low and eventually stopped in at Pease Pottage service station as I was crossing past the M23. The tank was virtually empty, the fuel light was on.

Filling up with fuel cost me £50.01.

It's the most expensive fuel stop I've *ever* had in *any* of my Lotuses. Taking non-Elise-variants out of the question (does the Europa have a larger fuel tank?) - has anyone beaten this?

Would make an interesting poll. I think my Exige has a 43.5 litre tank, but whilst I've kept my receipt from the petrol station as a Certificate of Insane Fuel Costs (hell, these Lotuses are meant to be cheap on fuel for their performance!!!), it doesn't have the actual number of litres I filled the tank with. I'm sure I had a few left because the car didn't run dry and neither did it start coughing or popping.

I use super unleaded because of the supercharger, but just the regular 'super unleaded' sold by whoever I stop at (I tend to prefer Shell and Tesco fuel). As it happened, Pease Pottage was a BP - I commented to the chap at the till, and he laughed and said that they'd just had a price cut, and the week before it was a few pence a litre more expensive!!!! The price cut rules out the conspiracy theory that the BP petrol was so expensive because they were trying to increase profits to pay for the inevitable enormous costs of cleaning up the Deepwater Horizon oil spill…..

Anyone else had similarly surprisingly extreme fuel bills when filling up their Elise / Exige / VX220 / 340R?

Don't include race fuel or BP's extreme 102 octane stuff, just pump fuel please

[Bebee]

Most so far was £38 and that was almost running out territory, as a matter of interest, do you notice any difference in performance when running on Super?

[Exige77]

Filled up today at local Shell £49.99.

I couldn't quite manage the £50.

Was £33~£35 to fill up from empty when I got it in 05.

Reday for Goodwwod tomorrow morning !!

Ex77

[Gavola]

used to live near Pease Pottage and it's one of the most expensive places to fill up in the country....what was the price per litre? Was in Glasgow last week.... £1.32 per litre!

[cyberface]

Bebee said:

Most so far was £38 and that was almost running out territory, as a matter of interest, do you notice any difference in performance when running on Super?

My immediate thought was 'must drive an S1' since IIRC the S1 has a smaller fuel tank (doesn't need as much, original design 118 bhp is a bit different to what Lotus ended up using, i.e. 240 bhp (allegedly) in my car).

But you've a Jim Clark SC Elise. And I'm pretty sure the S2 Exige and S2 Elise have the same size fuel tank… especially if the Elise is supercharged (though my handbook for S2 Elise & Exige, N/A and SC, says it's a 43.5 litre fuel tank for ALL models).

So you've either not needed a full-tank fillup for years which would be tricky since your car is only a year old… you must get some *VERY* cheap fuel if you've filled more than 40 litres for £38 I want to know where you shop for fuel!!!

As to the super unleaded - I haven't ever run it on regular unleaded so I have nothing to compare it against. I'm not doing it for either the potential performance gains (nil, until the intercooler gets hot and the engine gets fed red-hot intake air), or the potential economy benefit (the way I drive it? yeah, come on ). It's purely a cheap-ish insurance policy against det. I love superchargers - and have fitted a couple of aftermarket conversions as well as only moving from my beloved VX220 Turbo to the Exige because the Exige was now available with a supercharger. However the Rootes-type blower isn't my favourite - it is inefficient, and heats the air up significantly more than other positive-displacement designs. Hot intake air means lower density, more propensity to detonation, and a charge cooler is required, and at the extreme the ECU has to dump loads of fuel into the engine to cool the cylinders.

The Exige S (even my PP240) charge cooler arrangement is, as you know, an air-air exchanger mounted right on top of the engine. There's a scoop to direct air onto it, but it's not a perfect solution and the chargecooler can get hot, leading to hotter air entering the engine. The ECU will retard ignition if it detects det, which saves the engine, but leads to the infamous stories of N/A S2 Exiges cruising past supercharged Exige S models on trackdays

Funnily enough the Scooby, which whilst turbocharged and not supercharged (and hence in need of charge cooling *more*, given that turbos tend to blow hotter air than superchargers) has a similar arrangement with the charge cooler on *top* of the engine, not in the direct air flow, and fed from a scoop which has to turn the air 90˚. My two Scoobs dropped power noticeably when they got hot… but Subaru's tactic augmented ignition retardation (which reduces power) with pumping in LOADS of fuel (enthalpy of vaporisation cools down the intake charge nicely - water injection is a more economical and environmentally sensible similar approach). I've had under 10 mpg from a Scoob in midsummer under heavy load, and a *very* sooty tailpipe…


So basically I'm making a BIG assumption that the Lotus ECU retards ignition and potentially richens the mixture to avoid detonation when the intake temps get too hot on a *reactive* methodology - i.e. the ECU makes these adjustments when the knock sensor tells it that the engine is starting to experience detonation. If this assumption is correct, then using a fuel that resists detonation for longer (i.e. a higher octane fuel) will keep the ECU running normal ignition and fuelling settings for longer on hot trackdays, keeping my supposed 240 bhp at that level, and preventing nasp Exiges from making me look silly

However, this is a guess, and if the Lotus ECU actually just measures intake air temperature and load and *predicts* knock, then the grade of fuel I use will have no bearing on the onset of ignition retard and power loss. I don't have the technical expertise to find this out, sadly. I'd like to know as if I'm wrong then there's little benefit to the 98 until my warranty runs out and the car gets a chip & pulley and a map exclusively for 98…. I guess Scuffers would know but I doubt he's read this far through my long boring post


So whilst I can't help on experience with my current car, my previous 'normal' 220 bhp Exige S *did* try different fuels, and it did feel more lively on Tesco 99. But it's all subjective, and I doubt there's any real difference on the dyno. If the difference in the cost of fuel between a decent premium fuel and a super unleaded is a big deal financially and restricts the enjoyment of the car (unlikely for a chap with a new Jim Clark car) then it's insane to use super. It's more of an issue between cheapo supermarket fuel and brand-name fuel - they're all the same base fuel, but it's the additive pack that differs between retailers. Tesco 99 is the only supermarket fuel I'll put in the Exige unless I'm desperate - Tesco 99 has good feedback and every car I've tried it with has liked it. Otherwise it's Shell, most of the time.

Unless you've got a map specifically written to use the later onset of det from higher octane fuel, forget power increases. If you think you can *feel* better response from the engine (whether this is throttle response, mid-range torque, etc. - it won't be more power unless you've mapped for it) then it's worth doing. There are loads of threads on the pros and cons of 'super' fuel in Elises of various engines - lots on SELOC too with expert input from people in the oil industry. If you want tangible improvements in throttle response then a 2bular exhaust will have a lot more effect than using more expensive fuel...

The general conclusion seems to be that if your car hasn't got a knock sensor, and is mapped for 95, then putting 98 in is a waste of money. If the car has a knock sensor, and is mapped for 95, then the only benefit you'll get is when conditions get extreme enough that the 95 map itself starts to knock (very high ambient temps). However if the car has forced induction, I always use the highest octane fuel that's commonly available, as long as the price isn't silly (like BP's extreme 102 octane stuff). The dodgy Rootes blower and top-of-engine charge cooler on my Exige is hardly ideal for efficient, cool supercharging, and with the old car there was a striking difference in response and power between a crisp cold morning with cool intake air, and a midsummer trackday with high ambient temps.

My aftermarket Porker 993 supercharger conversion used an Eaton M90 (an inefficient Rootes type again) but with NO intercooler (!!!! yikes!) and that had loads of lovely low-down and mid-range torque and was a fantastic road car, but a midsummer trackday at Brands GP saw it *really* struggle with the intake temperatures… the power dropped right off and the piggyback ECU pumped loads of fuel through the 7th injector to cool the engine… didn't damage it (good old aircooled Pork, awesome engines) but I wouldn't take that chance these days with 8500 rpm motors.


Basically it's just force of habit, after a few turbo-nutter cars with chips that *did* work tangibly better on 98 than 95, I always use 98 in forced induction cars. And both of my cars are supercharged, and I haven't had a nasp motor for many years I know there's no more performance (unless mapped specifically so) but I'm hoping that the big brands' flagship 'high performance' fuels have superior additives for keeping combustion chambers clean, etc. and I like to put the best stuff in my pride and joy (well, both of them). If this turns out to be BS, and I'm wasting a lot of money for no reason, then I'll still buy a brand-name fuel because of the detergent additives, which are worth having.

[iwilson]

On a road trip across the US (Europe to NZ) in the S1, booked a track day at Laguna Seca - filled up with 100+ octane at the track $$$$. Blew a CV joint 5 laps later and wasted it all limping back to L.A.

[Bebee]

cyberface said:

Bebee said:

Most so far was £38 and that was almost running out territory, as a matter of interest, do you notice any difference in performance when running on Super?

My immediate thought was 'must drive an S1' since IIRC the S1 has a smaller fuel tank (doesn't need as much, original design 118 bhp is a bit different to what Lotus ended up using, i.e. 240 bhp (allegedly) in my car).

But you've a Jim Clark SC Elise. And I'm pretty sure the S2 Exige and S2 Elise have the same size fuel tank… especially if the Elise is supercharged (though my handbook for S2 Elise & Exige, N/A and SC, says it's a 43.5 litre fuel tank for ALL models).

So you've either not needed a full-tank fillup for years which would be tricky since your car is only a year old… you must get some *VERY* cheap fuel if you've filled more than 40 litres for £38 I want to know where you shop for fuel!!!:

My mistake. £48, and fuel is from Tesco or Sainsbury's.

Edited by Bebee on Sunday 6th June 16:04

[Echo66]

Regularly costs me over £50 to fill up form driving with the light on for a few days. Don't think its a reasonable barometer though. Fuel hideously expensive here atm. Over £1.34 for the good stuff.

[S Works]

Can't remember the cost (irrelevant now anyway as it was a couple of years back), but I once did Kent to Pool in Yorkshire on one tank in the Honda'd Elise (which was almost unheard of at 241 miles). My arse was twitching the last few miles!

[STEVEY_SC]

My S2 Exige costs ~£45 to fill up, this used to be £35 a few years back.

The doris's SLK350 costs £75 to fill up!

[Ganglandboss]

My most expensive fuel stop was when I unscrewed the cap, placed it on the mesh on the engine lid, filled up, paid, and drove off without putting the cap back! Eighty-two bd quid from eliseparts.com!

[Tyrant]

Ganglandboss said:

My most expensive fuel stop was when I unscrewed the cap, placed it on the mesh on the engine lid, filled up, paid, and drove off without putting the cap back! Eighty-two bd quid from eliseparts.com!

I can match that

[halfpenny43]

Echo66 said:

Regularly costs me over £50 to fill up form driving with the light on for a few days. Don't think its a reasonable barometer though. Fuel hideously expensive here atm. Over £1.34 for the good stuff.

Same here in the Netherlands. I filled up last week with BP super unleaded and 40 litres cost me EUR66, roughly GBP55