2m x 1m (6'6" x 3'3") plastic foil emergency blanket. Smaller than an envelope but amazing insulation properties. Tuck away in the glove box and if you break down, it will keep your co-pilot warm whilst you “fettle the old girl” or await the recovery wagon. We've found it reduces “I’m cold” wingeing by over 80%!
Use it as a mat to protect your clothing if you have to check underneath for leaks (the car, not the co-pilot!).
On exceptionally hot days use it across the windscreen whilst you are parked to keep interior cooler.
Mirror finish so can also be used for signalling search and rescue aircraft…!!
What's not to like?