Well there are quicker and longer ways of going about washing your car
the quicker you will get the more risk prone it will be... and its just that how much risk you are willing to take.
If you can source some items from abroad, then you should get some 1 galan concentrate waterless or rinseless products out there, like the Optimum No Rinse
you can read how to use them and there performance reviews over internet, just google it.
in simple you just spray on your car and wipe it off clean, Though it still has its risks but it is the most safest and quickest you will get with low cost on dusty cars, for dirty cars even they will recommend to use normal washing procedure
if you can not source anything from abroad then the quickest way is
do a full proper double bucket clean of your car.
wax properly
get a really good sealant and use it properly
then next time you can simply wash with pressure water, get spray bottle spray some shampoo and rinse with pressure water
Good sealant have a very good tendency to leave dirt off and thus making it really clean
the lower portion of the car is generally very dirty specially the bumpers near the tire area. use two bucket method on that area and then use the above procedure
this will give you atleast two good washes before you will need to reuse the two bucket system on the entire car
but plz mind it that if the car is dirty then use two bucket system or you will need more time to fix swirls that you might get in than the time you will safe.
if the car is only dusty then you can use the pressure washer method