The pollen filter is a right menace on right hand drive cars!
If it has any form of climate control or air con, it should have a filter in there.
The filter is fitted behind a oblong door in the side of the heater with two screws holding the door on.
Get down in the drivers foot well and look just to the left, just where the steering column enters the floor, you can see the back of the heater with a door in it.
You can get at it, but you'll huff and puff!
This is a lhd 500, it's similar to the Panda, but the pedals and steering column get in the way, some owners disconnect the column, but you can get to it without.
First, the lower trim down by your left foot needs to come off, there are a couple of screws holding it on, I seem to remember these being small Torq headed ones.
One screw on the filters door is easy to get at, the other can be a problem as you'll not get a socket on it due to the steering column.
The screws are normal spanner type, though the size, it's something odd like 5.5mm. (7/32" in american, see vid)
Best thing is a ring spanner with little crank on it. You can't really get anything like pliers on the head as it's recessed a little.
I cut an old socket down and drilled a hole through it to get a small screwdriver through it to turn it.
Once the door is off the old filter will pull out.
Note the arrow on the new filter (way the air flows) and pinch the new filter together, top to bottom to make it look like a double fan.
You should now be able to stuff it in the hole with just a little bend on it to get past the column, though you will have to hold the clutch pedal down with your third hand!
Once in it will expand back to normal and now you can faff about with the awkward screw again or just leave the upper screw to hold the door on in case you're mad enough to try it again at a later date!
Another couple of tips.
You might need a filter strap or chain to shift the old oil filter, it's usually on quite tight and it hard to get a grip on, it's on it's side, right next to the hot exhaust!
(don't worry about what looks like a massive dent in the front exhaust pipe, it's meant to be like that)
Oil the new seal on the new filter before fitting.
After you finished and the engines warmed up, recheck the filter for leaks and try and tighten it again with your hand, it will often nip up a little further.
While you are down there, wipe over the sump with an oily rag.
They are prone to rusting a bit and a thin smear of oil is as good as anything else, protection wise.
If you are removing the airbox to access the plugs or just to make the air filter change easier, be careful of the hoses.
There are two, a larger hose to the cam cover (to the left of the box) is held on with a Clic R clip
and
a smaller one (that comes from right up under the box to the lower, right rear of the throttle body) is just a push fit, but it's tight.
This smaller one isn't really noticeable and the barb up under the airbox it fits on it quite brittle and snaps easily, so best not to fiddle with that end of the hose.
Just follow it behind, through a holding loop and around to the lower right of the throttle body and disconnect it at the throttle body, it'll pull off with a bit of a tug.
If the airbox is off, clean the throttle body with some carb clearer.
The engine sucks up crankcase vapour (large hose from the cam cover, see above) and can cause the mouth of the TB to get a bit mucky and sticky.