Mpg down

lightning wrote: lt will be your new tyres. The side steps won't make any difference, neither will the new transfer box.

On the motorway in our 2020 Jimny l can just about keep the MPG above 40, if l sit at 65mph.
This is with the manual transmission. lt's not anything near our VW Up GTi where l could get over 60mpg at the same speeds.

The tyres fitted as standard will be designed for economy, so that Suzuki can claim 40+ mpg. lf you fit more aggressive tyres it's going to impact on that by a few % which is what you've found.

Thanks.

I agree I think it is mostly tyres, but I'm seeing 10-20% reduction in mpg. Which seems a lot. I don't recall seeing such a difference on other vehicles, even when switching to highly aggressive mud terrains. Not sure I can fully rule out the transfer box. I know people report they do whine, so something must be making that whine. And that whine may well be friction related. I'm not saying anything is wrong with the transfer box, but the replacement one is noticeably louder than the original one. And original one was faulty. So there could still be some drivetrain efficiency differences occurring, but I'll never be able to prove/disprove this.

I don't know why you are whining so much. I get around 23mpg with my 235 Muddies

I've noticed a small change after going from the standard Bridgestone HT's to 215 75 15 Hankook AT2's. Before I was getting around 7 l/100km and now around 7.6l /100km. In MPG this is around 40 to around 37. Bad mathematics says this is around 9% worse on the AT's.

l am sure it's your tyres.
But as you say, the only way to prove it is to borrow a set of standard wheels/tyres and try them on a motorway run.

lf the transfer box had that much excess friction it would be very hot after such a journey and you'd likely feel/smell the heat from it.

You can forget the T/box. To loose that much mpg through friction would see the oil in the box boiling off.

Different tyres from different makers, all use different patterns and different "rubber" compounds to juggle between life and grip. Think F1 tyres and how fast they wear and the grip they provide for acceleration, cornering and braking.

Roger

300, my daily commute involves around 40 miles of Motorway driving. On the OE dueler H/T's I would nudge 40mpg. Since having 215/75/15 BFG's on Steel modulars that's dropped to around 32-33 mpg. I haven't done any other modifications that would add weight to the vehicle, the added rotational weight is the culprit!