My 'go to' for blasting drones and vehicles? Indirect combat spells are my preferred, since you're going to do more damage against a Bulldog with Lightning Bolt than Powerbolt. Direct spells, after all, oppose your spellcasting with the vehicle's Body, and only your net hits are damage. So the Bulldog can easily be rolling more dice than you are, whereas the indirect spells have a defense roll, with net hits adding to damage, which are then resisted by the body+armor. That still isn't a great combo, but you use Force as the AP, which can make a big difference.
Trying to shoot a van (especially an armored van) with spells is a dicey proposition. But there are better tricks for mages. Here's my top 10 from just the core book, in no particular order:
1. Physical barrier at an angle to the road, forming a ramp, attempting to either launch the vehicle, tip it over, or otherwise make it crash.
2. Ice Slick in the road to force a Crash Test.
3. Do they have windows open to shoot at you? Fireball INSIDE the vehicle.
4. Illusions. If there is a metahuman driver, they will almost certainly react to a car coming out of nowhere at an intersection, looking like it will hit them.
5. Get a spirit to manifest inside the vehicle and kill the driver.
6. Remove sense (Sight) on the driver.
7. Light, blinding the driver.
8. Ignite on the driver
9. Influence on the driver (jerk the wheel sharply to one side as far as they can)
10. Armor on the vehicle you're driving, when you go to ram.
As you might notice, most of these have to deal with defeating the driver, or forcing a vehicle to make crash tests, rather than actually blasting the vehicle itself. That is because I come to Shadowrun by way of D&D, and any long time D&D player will tell you that you do not challenge a Barbarian's Fort save, a Rogue's Ref save, or a Wizard's Will save. That's just a bad idea all the way around. Instead, you hit a barbarian's Will save, since most of them skimp on mental stats. You go after a Rogue's Fort save, because they don't typically have much in the way of Constitution. You attack the Wizard's Ref save, because there is no way in hell he's got good physical stats.
Don't attack a person's strengths unless you literally have no other choice. Hit them where they're weak.