Volkswagen Beetles have 4 cylinders.
about 30
well from the time it was put into production the VW bug is still to this day the most widely manufactured car ever. there were so many VWs made that if they were all still around everyone in the us...
I get on average 45mpg using biodiesel in my 2000 vw beetle TDI. I am not sure about regular diesel, but I would guess it would be the same.
It is located on the drivers side, under the plastic cover for the wipers.