WASHINGTON — Automakers are cramming cars with wireless technology, but they have failed to adequately protect those features against the real possibility that hackers could take control of vehicles or steal personal data, according to an analysis of information that manufacturers provided to a senator.

Sen. Edward Markey, D-Mass., asked automakers a series of questions about the technologies and any safeguards against hackers built into their vehicles. He also asked about how the information that vehicle computers gather and often transmit wirelessly is protected.

Markey posed his questions after researchers showed how hackers can get into the controls of some popular cars and SUVs, causing them suddenly to accelerate, turn, sound the horn, turn headlights off or on and modify speedometer and gas-gauge readings.

The responses from 16 manufacturers “reveal there is a clear lack of appropriate security measures to protect drivers against hackers who may be able to take control of a vehicle or against those who may wish to collect and use personal driver information,” a report by Markey’s staff concludes.

Nearly all new cars on the market today include at least some wireless entry points to these computers, such as tire pressure monitoring systems, Bluetooth, Internet access, keyless entry, remote start, navigation systems, WiFi, anti-theft systems and cellular-telematics, the report said.