both cars have the potential to be modded for performance. the jetta TDI (TURBO direct injection) does have a turbo as well, so there is the potential for upgrades. in the end, the 1.8t could be made much faster than the TDI, but if you're considering gas mileage as well the TDI might not be a bad idea. I have a VR6 jetta and i've been wishing for awhile that TDIs were legal in california. i've been driving the jetta more than my allroad just because of gas prices in SoCal.. and to keep the miles off of the allroad which is a lease. anyway... you shouldn’t get either car in auto... good luck
