Are you experiencing actual lag or is it frame rate drops that make you think it is lag? Some people don't know the difference and frame rate drops tend to look like lag, when they are not. Before I started playing on PC, I used to think that alot of frame rate drops were lag.
Frame rate drops would make sense in your case, due to the fact that your vehicle is moving much faster than your soldier and has to render more of the background / other parts of the map much more quickly and uses alot more graphics rendering power, which can lead to frame rate drops if you have a lower quality GPU or are on console.
i'm pretty sure my problem is high ping:
i have an fps counter and my fps are around 60; i have a symbol on my left side of the screen (similar to this one: http://image.shutterstock.com/display_pic_with_logo/299362/268369964/stock-vector-no-signal-sign-bad-antenna-no-internet-connection-concepts-jamming-interference-icon-268369964.jpg) and sometimes a yellow notification appears, it says thet my internet connection is bad and the game could be unplayable ☹️
Ok I know what you are talking about. One thing to try, is while on the in-game menu, go to your settings tab. After that go into the "EA settings" and switch your region to your closest one. If you are in the US, try both West US and East US. See if this helps with your lag at all.
