I'm not sure that's the case. I connected via my iPhone's hot spot (LTE) and web sites loaded about four times as fast.
I should also note that I installed a Wilson Electronics Mobile 4g Cellular Signal Booster Kit (which works with 3G as well), which has it's own antenna (mounted on the front crash bar under the nose cone). So maybe the slow speed has a lot to do with the poor antenna embedded in the side view mirrors.
I have to say that I'm very impressed with the coverage the car can achieve now. It used to be that the car had worse 3G reception than my phones (Samsung & LG); now I can say that the opposite is true -- when my phone has no coverage, the car will have 3-4 bars.