Audi A4 vs BMW 3 Series (2017-2024 vs 2019-2026): Which Should You Buy?

These are close to a dead heat — both score 7/10 for reliability, both files land on a "buy it" verdict, and both share the same core weakness: brittle plastic cooling-system parts that seep coolant slowly and get expensive if ignored (Audi's water pump/thermostat module runs $700-1,500; BMW's oil-filter-housing/vent-hose failure runs $350-4,000 and is now the subject of a Feb 2026 class action). The difference shows up in what happens when things go wrong: the Audi's only "severe"-rated failure is the S tronic dual-clutch transmission ($2,000-5,000) if the ~40k-mile fluid service was skipped, while nothing in the BMW file carries that severity rating for an owner-pays repair — BMW's worst-designated items (starter fire-risk recalls, 330e battery recalls) are free recall fixes, not bills, provided you verify them by VIN before buying. So: lean BMW (M340i, per its own file's pick) if you're willing to run a recall check first, and the Audi is just as defensible if you can verify full S tronic service records — a car with no transmission paperwork is the one to walk away from on either side.

• •Both share the same failure signature — brittle plastic coolant-system parts that seep slowly (Audi's water pump/thermostat module vs. BMW's vent hose/oil filter housing) — so neither has an edge on the pre-buy coolant-crust inspection; budget similarly either way.
• •Audi's dual-clutch S tronic is the one 'severe'-severity owner-pays risk documented in either file ($2,000-5,000 mechatronic failure on fluid-neglected cars); BMW's conventional ZF 8HP torque-converter automatic has no comparable severe-rated failure in its file — a real durability edge for buyers who might skip maintenance.
• •BMW carries more pre-purchase VIN homework: a rolling series of starter recalls (fire risk in rare cases) plus 330e battery-contamination recalls, all free fixes but unverified ones are a real risk; Audi's recalls (backup-camera software, seat-heater cable) are comparatively minor.