If you have a car that doesn't come equipped with a TPS resistive senor for use with your data logger, you can use one of these which appears to be fully sealed against water as most automotive sensors are, here is one you might consider:

http://www.beiduncan.com/pdf/m...6.pdf

They can be had at around $40-$45 from Mouser.com

http://www.mouser.com/search/R...cards