yes, but you can only "buy" cars you've already collected.

South west at the top of the Eiffel Tower,and north east in a farm somewhere.Ive only used the tower now i have the gold perk and can hide in any hiding zone if im out of sight.

go to freeplay spots in countryside (to avoid civilians killed),

turn on infinite health + ammo,

if you had Wulf tank (one with two cannons) use it, if not, simple rocket launcher should do the trick,

start blowing everything,

wait for Nazi vehicle response the alarm,

running around + blowing the reinforecments but don't go so far (or you'll escape red zone)

you should get your level 5 alarm in about 10 minutes.

IMO, if you stay in one place, no matter how many krauts you kill you'll still stuck at level 4.

but if you're more hit & run, the better chance bigger Nazis' vehicle to appear.