Mazda MX5 - Why such low MPG?

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Tue 2 Apr 2013 23:12
Mazda MX5 - Why such low MPG? - galileo

Just been talking to a friend who has a 1.8 MX5, it seems 30 - 35 mpg is the best one can expect from these, even a 70 mile trip on uncongested level roads returns about 30 - 32, driven sensibly.

The 12 year old Alfa he just disposed of did better, my i30 hatchback will easily give 40+ on the same journey.

Considering the light weight, low frontal area, similar mph/1000 revs in top, we find it hard to understand why this is so.

We checked transmission efficiency at the Rototest website, shown as 88%, more or less average, any ideas as to why MX5's don't seem to be very frugal on petrol?

Edited by galileo on 02/04/2013 at 23:24

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Wed 3 Apr 2013 09:44
Mazda MX5 - Why such low MPG? - Leif

I've wondered the same, and it is the reason I did not consider buying one. Surely if city cars can do 60mpg, and the VW Up GT can reportedly do 60mpg, you might expect better.

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Wed 3 Apr 2013 10:59
Mazda MX5 - Why such low MPG? - ohsoslow

My '99 1.8 Mk - 2 will get 34 -36 mpg, not driven gently and with the roof down for 99% of the time - it gets a bit better with the roof up apparently.

It was not bought for fuel saving purposes. I agree that this is not particularly good and although Mk- 3s do a bit better they are not very economical compared with other cars. Top gear could be better for motorway driving but is fine for my twisty A / B road journeys.

Regards

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Wed 3 Apr 2013 21:32
Mazda MX5 - Why such low MPG? - Bobbin Threadbare

I get 40mpg out of my 5 year old 1.8l MX-5. I do not drive it for fuel economy but the worst I get if I burn it is about 37mpg. I don't think that's too bad actually and let's face it, they aren't built for frugality, they are built for some fun! Mazda are also honest about the mpg they will get - it's not offered crazily over-inflated figures that garner complaints about accuracy. I reckon I could get more mpg out of my MX-5 if I drove it like an OAP.

Could lob a can of Redex or somesuch in and clean out the muck every so often; that improves mpg a bit. The weather is also a factor.

Edited by Bobbin Threadbare on 03/04/2013 at 21:33

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Fri 5 Apr 2013 09:05
Mazda MX5 - Why such low MPG? - Falkirk Bairn

>>only 32mpg!

Are you sure the brakes are freeing up - a sticky piston might have you wearing discs and pads and giving low mpg.

A few years back my average mpg seemed to drop by 5/6 mpg.........at a service they noticed a scuffing of rear disc - free 'd up the pistons / greased all round - I think they charged me £40 on top of servicing cost.

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Fri 5 Apr 2013 10:58
Mazda MX5 - Why such low MPG? - galileo

>>only 32mpg!

Are you sure the brakes are freeing up - a sticky piston might have you wearing discs and pads and giving low mpg.

A few years back my average mpg seemed to drop by 5/6 mpg.........at a service they noticed a scuffing of rear disc - free 'd up the pistons / greased all round - I think they charged me £40 on top of servicing cost.

My friend, like myself, worked for many years in engineering; he is an apprentice-trained fitter and rebuilt a Lotus Elan from a new backbone chassis up, assures me he's checked everything and other owners say this is about what they expect in consumption.

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Sat 6 Apr 2013 01:23
Mazda MX5 - Why such low MPG? - Avant

Moved to Motoring - I've no idea why this was in the non-motoring section.

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Sat 6 Apr 2013 07:00
Mazda MX5 - Why such low MPG? - NARU

I get around 33mpg from my 2.0 mx-5 overall. I can get more on a motorway run - as much as 38-40.

I agree it seems low, but I'd put it down to mine still being a little tight (its only done 8,000 miles). I'm also assuming that the fuel injection is set up for fun rather than frugality.

I guess I could raise mine with some eco tyres, but will not be going that way.

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Sat 6 Apr 2013 10:56
Mazda MX5 - Why such low MPG? - NARU

Official mpg figures here ...

www.honestjohn.co.uk/road-tests/mazda/mazda-mx5-20...e

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Sat 6 Apr 2013 12:44
Mazda MX5 - Why such low MPG? - balleballe

There's not a 'ticking' sound coming from the manifold is there?

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Sat 6 Apr 2013 14:23
Mazda MX5 - Why such low MPG? - madf

I suspect the aerodynamics are rubbish. - revised 2012.


And as it's a sports car which is often used as a second car.. which option for engine tuning does Mazda choose?

Responsiveness and accleration

or fuel consumption..

Remember in its own market and its major export market (US), the Mazda's 35 mpg is irrelevant with cheap cheap petrol. (In the US, it's brilliant!)

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Sat 6 Apr 2013 16:58
Mazda MX5 - Why such low MPG? - Bobbin Threadbare

I don't think the aerodynamics are rubbish but it's certainly tuned for acceleration. Mine is well run in now - 68k on the clock and used as a commuter car. I do 55 miles a day in it.

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Sat 6 Apr 2013 17:01
Mazda MX5 - Why such low MPG? - 72 dudes

My 2007 Mk3 MX5 1.8 has averaged 37.9 MPG over the 2 years I've had it, with a high of 40.6 and a low of 33.6 (always done brim to brim)

Older 1.8s up to 2005 had a different engine and 32 is about right for them.

My worst tankful of 33.6 was at the last fill-up last week and goes back about 3 months. Do not under estimate the effect of the very cold weather we have been having.

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Sat 6 Apr 2013 18:18
Mazda MX5 - Why such low MPG? - johncyprus
I had two of these way back, the 1999 1.8S would only do about 33mpg whereas my 2001 1.6 would do nearly 40 mpg and the 1.6 had a lovely sweet engine.

Slightly off topic I now have a tweaked 1996 MG MGF which would make my old 1.8S seem pedestrian. Once you have one of the new multi layered gaskets fitted to the cylinder head the MGF is sorted and the K series engine once warmed up loves to rev....and driven sensibly 40mpg is easily achievable.
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Tue 9 Apr 2013 15:30
Mazda MX5 - Why such low MPG? - TeeCee
Slightly off topic I now have a tweaked 1996 MG MGF which would make my old 1.8S seem pedestrian. Once you have one of the new multi layered gaskets fitted to the cylinder head the MGF is sorted and the K series engine once warmed up loves to rev....and driven sensibly 40mpg is easily achievable.

Variable valve or "cooking"?

A colleague bought a TF a few years back and I test drove a few with him. The ordinary one was chirpy enough and he bought a very tidy one of those. We did get our paws on a VVC one for a while though and I have to admit to being deeply impressed. It wasn't so much the additional power, although that was noticeable, but the way the power was delivered across the rev band was truly astonishing. Absolute bootfuls of grunt all the way up the dial and no evidence at all of the peakiness normally associated with engines in a higher state of tune. For footling around gently I reckon it was actually better behaved than its lower performance counterpart.

One day I'll see the right one knocking around while I have some spare cash and buy it.

I suppose that Nanjing now own that AP / Rover VVC system and we'll never see it again.....

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Wed 4 Sep 2013 18:40
Mazda MX5 - Why such low MPG? - rogerzilla

Mine's averaged over 41mpg from the first seven tankfuls, and it's not run in yet. Mixed driving but no heavy congestion or short trips. Driven up to the legal limit and (now it's running in) regularly taken to 70mph in 3rd. That's with 17" wheels which won't be as efficient as the standard 16" ones.

It sounds as if something is wrong with the car in the OP. Outside bet: some Japanese cars in particular run very badly and give 4-5 mpg less on some brands of petrol (BP and Sainsbury's in particular). The additive package doesn't seem to agree with them. Try Shell, Esso or Texaco.

Edited by rogerzilla on 04/09/2013 at 18:42

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