Having driven back from 24/12 I noticed that considering it was mostly motorway driving my mpg was below normal.

Not knowing too much about car but using some common sense I jacked the car up at each wheel and spun it round to see if the brakes were dragging (bike logic!). The front wheels spin fairly freely but the back two there's way more resistance.

Firstly there is this likely to matter and affect the mpg? Also could it just be because I'd only just released the hand brake (does it take some time to push the pads away or something?).

Any help/advice mcuch appreacited, the front pads were replaced recently in a service but not the rear as apparently have some life left.

Thanks in anticipation.

How stiff are they?

I doubt it makes much difference once you get a 1 and a hlaf ton lump of metal up to 70mph.

Did you have bikes on the roof rack or softer tires than usual? That could make a difference.

Around 3 times as stiff as the front ones? When I spin the rear wheels I can feel the brakes rubbing but as you say not sure how much differece it would make at 70mph etc… A good strong spin and it stops before 1/2 turn.

No bikes on roof etc… and just camping stuff and bikes so not much more laden than usual.

What car? Etc etc. Yes it will make a huge difference – especially as when the brakes heat up they are likely go seize on more. Most likely cause is the handbrake mechanism if both rear wheels are seized on.

were they very hot or smelled of hot oil? if so they are probably binding, this will reduce your fuel consumption ( think how hard its is to ride with a brake binding!). can be caused by alsorts and depends on manufacturer and type so from the sounds of it you need to get it to a garage….

It's a passat estate – handbrake did occur to me as both wheels affected but idea didn't go any further due to lack of knowledge hence post here!

Is there anything simple I can do/test before forking out more money at the garage…?!

poss handbrake cable , try taking the handbrake on and off to see if the cable is free ? should only pull up about 5 clicks .

When you say cable is free does that mean looking under the car?

In reposnse to previous question it didn't seem overly hot but it was raining pretty much all the way home?

Disks or drums?
I'm guessing disks if it's a passat estate.

I'd be surprised if it was the handbrake cable as the pads would quickly wear a bit and release it I would have thought.

If your brakes are binding a bit there should be enough heat generated to heat the wheels up after a few miles of normal brake use, so try that. Could try taking the wheels off and hosing around the discs in case it is just grime causing the pistons to stick – a la bikes.

Your increased petrol consumption could just be from driving with a lot of kit in the back on too soft tyres

Handbrakes typically work on a rear drum separate from disc drakes.

If it was rubbing to the extent of causing lower mpg would it get really hot??

As you say I would have thought, as with bikes, any considerable rubbing with such momentum behind it then the pads would either burn away and stop rubbing or just be forced away from the disc. However I can assure you if I jack up the rear wheels and spin them they spin nowhere near as freely as the front ones as can feel the resitance as it's turned.

Not necessarily, depends how good they are at dissipating heat. Binding enough to stop after half a turn from a big spin is seriously binding, a big spin sees most wheels turning ~6-7 times before coming to a halt.

Car discs normally do require a little nudging away from the discs by the action of driving to free up, but that normally happens the moment you spin the wheel – you shouldnt really notice it when jacked up. You probably just have gack on the slider pins in the caliper preventing them releasing properly – rear brakes are a lot less used and tend to cause more problems than their frontal counterparts.

If it was rubbing to the extent of causing lower mpg would it get really hot?

I would have said so – if it could significantly reduce MPG, the brakes would be cooked and have failed completely (unless they are ceramic, which they aren't).

I would suggest that if it was the brakes, then you need them fixing and new shoes/drums or pads/disks putting on too.

Assuming they are binding is there a quick fix or do I need to trot along (again) to the garage to get the rear brake parts replaced…?

It has been known for rear calipers to sieze on the Audi/vw's. The handbrake works on the disc not a separate drum. You could try pulling the actuating lever back on the caliper ( ie away from the nipple on the handbrake cable )to see if this frees off the wheels. If it is this it will probably need a new caliper. They are not too expensive from what I remember.

happened on my bora, the caliper on a rear disc has pistons which self adjust on a screw thread which is connected to the handbrake cable, they can seize. you can tell by taking the caliper out (remove the pads) and rotate the piston ( you may need a special tool to do this) it should rotate either direction freely…..sound like a pain in the ****? well not really but if you arn't sure the get it to the garage!!!

it went to the garage this morning…!

Being an old bugger, when I drive long distances, fully laden, I often go round and touch the wheels at a stop to see if there's any heat build up.

I don't know why, or what I'd do if a wheel was hot. But it makes me feel responsible.

I always check my tyres at service stations on long journeys. 😉

*once*, I found a big bulge on one of them. So that's my checks justified I thought as I drove another 100 miles+. But that's scottishland for you, they've only got two tyre repair shops in the entire country and one of those doesn't sell tyres for sports cars.