It will cost you more than a 2wd just because insurance companies believe that people w/ 4wd are more likely to take them out in bad weather and other unfavorable driving conditions (higher chance of accidents) and 4wd vehicles are much more likely to roll over when compared to regular cars. Just exactly how much more the insurance company will charge you depends on a lot of different factors (i.e. your age, driving record, the current vehicle you are driving- an older vehicle only worth $3,000 will be a lot cheaper to insure than a new vehicle costing $25000, etc.). I doubt your insurance will double or anything like that- but it probably will cost you $20 or $30 more per month (assuming you are currently driving an older 2wd vehicle).
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2004 Toyota Tacoma (Xtra-Cab, 4wd, TRD Offroad, SR5, 3.4 V6, Auto...)
Flowmaster 50 Deltaflow Series
Deckplate Mod
Grey Wire Mod
More to come!!