[donc]

Hiya Bob - Sorry you seem to have misread my post - Just to refresh... I did not say your speedo and odometer were calibrated the same; I said they were "mechanically linked so variances in one equally impacts the other", and this is correct - both are driven by the same mechanical system linked to the rotation of gears in direct ratio to the rotation of your cars wheels; the diamater of which can change dramatically due to tire size and pressures, hence the accuracy of both odometer and speedo can equally change in direct proportion.

That the calibration of your odomoter presents a different percentage of error doesn't change this base fact. By the way this isn't an opinion based on home testing of one vehicle (although I commend your enthusiasm!), I am an automotive engineer and have some credibility in this area. I stand by my original observation - a GPS provides a more accurate measure than an odometer if you are interested in knowing the true distance your vehicle travels.

Cheers

[donc]

That's interesting don.
i know my i30 speedo is a bit happy , just thought the trip reads fairly close. I know about Tyre's expanding but don't think it is that dramatic, i run my tyres at around 40psi ( thats if my tyre pressure gauge is still accurate.)
Those imates are good.

Hi Lakes,

The change is a lot more dramtic with low tire pressures than high (eg 40 psi), because tire expansion is limited by the radial belts - although an under-inflated tire (eg 15 or 20 psi) will 'fold' when rolling and presents a smaller rolling circumference thereby changing your gearing and overall speedo/odometer accuracy by a not insignificant factor. A more dramatic change occurs when people change the diamater of tires by fitting higher or lower profile tires or change the tire and rim sizes (eg higher profile winter-treads as mention earlier).

Of course were we talking race cars we would also add vehicle geometry to the equation (one reason race car speeds is calculated by satellite navigation systems nowadays)... but not so relevent here.

[EymaTeapot]

Question Don, Bob,Lakes or anyone else with an opinion on the matter.

I have put 18" alloys on my i30. Naturally, they are coupled with a lower profile tryer, 225/40 I think. According to my gps, the speedo is out about 6%.
My question is though, should I be running a higher or lower tryer pressure than is normal.
I currently am running the tryers at around 36psi all round. Maybe this is a bit low?

[Dazzler]

I.M.O. 36PSI is about right (that's what I run in my 16" ) with your lower profile tyre I would imagine 38 or 40 would be too harsh....and cant imagine would make measurable difference in economy or handling..

Eyma,

I reckon there's a thread somewhere that looks at tyre pressures that gives lots of info about finding the right pressure.  

I'm no expert on pressures.  I'm currently running 38psi in the standard kit on 16" rims, even though the plate says 32psi.  Seems to be about right I think.

Bob

[donc]

Hi Eyma - I would talk with your tire supplier or retailer, and wouldn't be too worried about the impact on your odometer etc. Of more importance is the handling characteristics of your vehicle and tire 'life'. Over-inflate and you will wear the centre of the tire, under-inflate and you will wear the edges. Either scenario reduces the handling characteristics of the tire as well as shortening the life - I would go withr the manufacturers recommended pressures.

[EymaTeapot]

Thanks for the Tips,
36 psi seems about right. The ride is a bit harder than standard as you would exspect. I also had it lowered about 35mm so this also makes the ride a bit harsher but it has improved the handling. Not that there was anything wrong with the handling, even the critics who have for many years critisized Hyundai for their handling praise the dynamics of the i30.
Sorry... this thread is meant to be about petrol economy....oops

[donc]

Next time you are near a 'Super Cheap Auto' consider buying a tire depth gauge - should only set you back $5 or so, and can save you $ hundreds across the life of your tires if you check the depth every few weeks. Look for variations across the tread - a high or lower centre indicates pressure problems - high-to-low across the tread (or the reverse) indicates wheel alignment issues... feathering suggests hard cornering, braking or acceleration and maybe the type of tire isn't suited to the combination of driver and car.

PS - Tires are directly related to fuel economy!

[donc]

A 600 km run today so 'borrowed' my lovely lady's i30 again... wet weather so probably taking it a bit easier than usual, but was still surprised to look down at the dash and see the L/100km reading below - yep that's 5.8 litres per 100 k for a 2.0 litre engine. I'm not soft on cars and I've found the i30 usually runs at around 6.4 L/100k (up to 8 when I'm pushing it real hard) so this was pretty good!

PS - I don't drive in the city at all - all my driving is in the country so my fuel consumption is probably not typical, but still it's quite a bit better than what I get out of our 2.0 litre Mazda (usually runs around 8L/100k).

[donc]

Lower L/100km might be more of a priority for some than others, but the above sparked my interest so I tried a little experiment after this post last night...

Having had another 50 km to drive (the last leg to get home), I reset all the computer settings and drove a steady 90 kph (94kph by the speedo) for the remainder of the trip.

It took a few km's for the everything to stablilise. For the first 15 km the computer settled on 4.9 L/100k... I then came to a large incline (a small mountain climb), and by the time I was at the top it had risen to 6.1 L/100k (still running at 90kph). Roughtly 30 km in it settled on 5.4 L/100k and stayed there for the rest of the trip.

That's not my normal driving style and I would find it hard to sustain an average of 90kph around here... still I guess an average 80kph would present even lower readings... Seems these cars can be be driven very economically if we choose to do so.

I wonder how low I could get it if I really tried? (has anyone?)

PS - Fuel consumption also seems to be lower on average than when we purchased the car... Not for the first time I'm thinking these cars must be de-tuned at purchase to prevent early engine wear while they are being run-in by possibly novice drivers (not uncommon for manufacturers to do this - Ford has been doing it for years) and reset to proper tune paramaters during the first dealer service.

Just got back from a trip from Parramatta to Woolongong and back, about a 160km round trip. There is about a bit of city driving, then some motorway driving.

Using the ScanGaugeII I achieved a 6.5L/100Km whilst the i30 was giving me a figure of 7.1L/100Km. I also filled up just before leaving and had put in the petrol price and got a figure of approximately $22 (AU) for the round trip, the petrol was $1.56/ltr.

[harakas]

hello to everyone!!i drive an i30 (1.4 109ps petrol engine) and my meter shows 7.780 km so far.my consumption is 7.2 but no mater how slow and smooth i drive it won't go any lower.i start to worry if these readings are for real at all.i drive a lot on highways trying not to accelerate too hard but nothing changes.is there something wrong?

[eye30]

Welcome harakas to the forum.

If you read other threads on this it appears that the fuel consumption will get better as the engine beds in so no need to be unduly worried at present.

By the way can you put your location in your profile so the map can be updated.

[Dazzler]

hello to everyone!!i drive an i30 (1.4 109ps petrol engine) and my meter shows 7.780 km so far.my consumption is 7.2 but no mater how slow and smooth i drive it won't go any lower.i start to worry if these readings are for real at all.i drive a lot on highways trying not to accelerate too hard but nothing changes.is there something wrong?

Hi harakas (and a warm welcome to the club)

If you do not reset the Trip Computer by holding the button down for a few seconds on the function you wish to clear the computer will just work out the average since last re-set. Therefore the longer you have driven the less it will change.

Try resetting it and after say 20 odd Kilometres (or miles) you should start to get a truer readout for your current results....

Hope that helps  

[harakas]

thank you and "top" for helping advice!!it really worked and i finaly have a more clear view for my car consumption.by the way i live in athens (greece).i think it will be a great idea if you come and visit greece in the summer with your i30!!believe me you will spend the most wonderfull time of your life,especially if you visit any of our lovely islands!!

[eye30]

i live in athens (greece).

To help when replying etc can you update location in your profile.

[Dazzler]

thank you and "top" for helping advice!!it really worked and i finaly have a more clear view for my car consumption.by the way i live in athens (greece).i think it will be a great idea if you come and visit greece in the summer with your i30!!believe me you will spend the most wonderfull time of your life,especially if you visit any of our lovely islands!!

No Problems... My Late mother was born in Naples Italy (Well actually Caserta in the hills behind) and I have a brother living in Monaco so I might get there for a look one day but would cost thousands to take the i30 there  

[buddyforu]

My last tank averaged 7.277L/100km. Awesome!!!

[teamgeorge]

I've had a couple Jap Turbo cars in the past the used the Hi Octain 98 and its brilliant, especially when I tried a tank of plain jane 91, i got near 200km and better performance from the 98 octain stuff... i tried trialing my gfs Mazda 3 with hi octain and couldn't justify the extra 40km from a tank with a $17 difference in cost. in saying that the engine was designed for the 91 octain (as was the i30) but it's good to see some positive results, i might test the Mazda again in the near future...

the engines must enjoy the cleaner fuel... whats the price difference in a full tank of i30?

[dacho]

My car has 650 km and consumtion is 9,8 lit on 100 km  

[Dazzler]

My last tank averaged 7.277L/100km. Awesome!!!

Hi Buddy, Welcome back  

[L30N]

I've never reset the trip computer since the car was new. In the first 3 months we have done 3100 miles or 5000 km. Consumption is showing 36 mpg that's about 7.85 l/100 km mainly town driving. Thanks to google for the conversions

[eye30]

I've never reset the trip computer since the car was new. In the first 3 months we have done 3100 miles or 5000 km. Consumption is showing 36 mpg that's about 7.85 l/100 km mainly town driving. Thanks to google for the conversions

According to the HY UK web site you are returning the Urban figures (37.2 MPG).

How does that compare to what you expected - Good or bad?

[Diva]

On about a 2.5 hour drive down south i got as low as 6.9L/100km.... but i must say my city driving consumption is terrible.... the highest it has been is somewhere in the 10L/100km. I must be a bit of a lead foot. After driving a 1.5L car for 10years its weird to have much more grunt.

[SergeyZdravkov]

My last tank went 8.87/100 km only city driving  :roll:

[bumpkin]

It's much colder in Aberdeen now and I have noticed a severe drop in consumption to average of 31mpg in town driving from about 36mpg.  I am trying to measure the effect of the heated leather seats, but some mornings have just been too damned cold to not switch them on!!

[eye30]

I have noticed a severe drop in consumption

Likewise mine has dropped from 54mpg to 51.7mpg.

[Shambles]

I have noticed a severe drop in consumption

Likewise mine has dropped from 54mpg to 51.7mpg.

I guess I must be just lucky, what with this tuningbox fitted. Averaging 64mpg at the mo *whistling*  

[L30N]

I've never reset the trip computer since the car was new. In the first 3 months we have done 3100 miles or 5000 km. Consumption is showing 36 mpg that's about 7.85 l/100 km mainly town driving. Thanks to google for the conversions <img src="{SMILIES_PATH}/icon_e_smile.gif" alt="" title="Smile" />

According to the HY UK web site you are returning the Urban figures (37.2 MPG).

How does that compare to what you expected - Good or bad?

A bit disappointed, however most of our journeys are less than 2 miles and the trip shows an average speed of 24mph.

[Rubix]

I've never reset the trip computer since the car was new. In the first 3 months we have done 3100 miles or 5000 km. Consumption is showing 36 mpg that's about 7.85 l/100 km mainly town driving...
A bit disappointed, however most of our journeys are less than 2 miles and the trip shows an average speed of 24mph.

Reset your trip, your engine is now broken in, you'll find an improvement of around half a litre/100km I'd expect, now your engine is broken in a little.