From the July/August 2026 issue of Car and Driver.

Halting an intoxicated motorist before they start their vehicle seems an effective method to cut down on deaths. This is the reason the 2021 Infrastructure Investment and Jobs Act directed that new cars include sophisticated systems to stop impaired operation. One major issue remains: The needed technology is not yet available.

Ignition interlock devices already exist and are commonly fitted in vehicles of repeat offenders under legal mandates. However the new regulation demands passive detection of impairment without a breath sample and then restricts or stops the car from functioning. Options under study involve skin sensors at common contact points to gauge alcohol levels, cabin air analysis for breath vapors, or monitoring of steering patterns and eye movements to spot fatigue or distraction.

Jonathan Wiggs/The Boston Globe | Getty Images

Resistance has emerged in Washington. The Alliance for Automotive Innovation warns that even rare false positives from early versions could hinder compliant drivers.

Several members of Congress object to the mandate. Representative Thomas Massie of Kentucky has been especially outspoken. The House rejected his recent proposal to cut funding for this part of the law. He has joined efforts to repeal the requirement and contends the system would violate personal freedoms while questioning what happens once a vehicle deems a driver unfit. Some critics speculate the car might alert police though NHTSA has not finalized any response protocol. Actions such as alerts or limits could vary by impairment type and might occur before or during travel.

The original IIJA schedule set a 2028 model year deadline for automakers. That target will almost certainly slip. NHTSA must issue yearly updates on the delay for a decade after the law took effect in late 2021. Progress so far suggests the chance of built-in systems in upcoming models remains slim.

Ever since David was a wee Car and Driver intern, he has kept a spreadsheet listing all the vehicles he has driven and tested. David really likes spreadsheets. He can parallel-park a school bus and once drove a Lincoln Town Car 63 mph in reverse. After taking a break from journalism to work on autonomous vehicles, he is back writing for this and other automotive publications. When David is not searching for the perfect used car, you can find him sampling the latest in gimmicky, limited-edition foodstuffs.