Most owners assume the line is drawn around appearance. It is not. Section 52(1) provides that no owner of a motor vehicle shall so alter the vehicle that the particulars contained in the certificate of registration are at variance with those originally specified by the manufacturer. That is the test, and it explains results that otherwise look arbitrary. A change that leaves the registered particulars intact is usually unremarkable. A change that does not is an alteration whether or not it is visible from the outside.
The alteration provision, and its exceptions
Section 52 carries three exceptions worth knowing. Modification of the engine or a part of it to run on a different fuel or source of energy, including battery, compressed natural gas, solar power or liquefied petroleum gas, by fitment of a conversion kit, is permitted subject to prescribed conditions. The Central Government may prescribe specifications and conditions for approval, retrofitment and related matters, and where it has done so the manufacturer's warranty is not to be treated as void for that reason. And under Section 52(2) a vehicle may, with the subsequent approval of the registering authority, be altered into an adapted vehicle, subject to prescribed conditions. Section 52(3) then requires an owner who has made an alteration without approval to report it to the registering authority within fourteen days and forward the registration certificate so that the particulars can be entered.
The penalty sits in Section 182A(4). An owner who alters a motor vehicle, including by way of retrofitting of motor vehicle parts, in a manner not permitted under the Act or the rules and regulations, is punishable with imprisonment which may extend to six months, or with a fine of five thousand rupees per such alteration, or with both. Per alteration is the phrase to notice. Section 182A(1) separately catches a manufacturer, importer or dealer who sells, delivers or alters a vehicle in contravention of the construction chapter, with a fine of one lakh rupees per vehicle.
The specific rules people trip over
- Glass tint. Rule 100(2) of the Central Motor Vehicles Rules, 1989 requires the glass of the windscreen and rear window of every motor vehicle to be maintained so that the visual transmission of light is not less than seventy per cent, and side window glass so that it is not less than fifty per cent. That is a figure a meter can measure at the roadside, which is why it is enforced so consistently.
- Horns. Rule 119(2) provides that no motor vehicle shall be fitted with a multi-toned horn giving a succession of different notes, or with any other sound producing device giving an unduly harsh, shrill, loud or alarming noise. Rule 119(3) preserves approved sound signals for ambulances, fire fighting and salvage vehicles and vehicles used by police officers and Motor Vehicles Department officers in the course of their duties.
- Exhausts. Section 194F punishes a driver who sounds the horn needlessly or continuously, or in an area with a sign prohibiting it, and, in clause (b), one who drives a vehicle which makes use of a cut-out by which exhaust gases are released other than through the silencer, with a recorded warning for a first contravention and a civil penalty of Rs 1,000 to Rs 2,000 for a subsequent contravention from 15 August 2026.
- Anything that makes the vehicle a danger. Section 190(1) punishes driving, or causing or allowing to be driven, a vehicle with a defect the person knows of or could have discovered by ordinary care and which is calculated to make the driving a source of danger, with a civil penalty of Rs 5,000 under the amended provision. Where that defect causes an accident involving bodily injury or property damage, the provision retains criminal punishment, with a separate repeat-offence consequence.
Section 200 lists the compoundable offences. Sub-sections (1), (3) and (4) of Section 182A remain in the amended list. Section 194F does not. For Section 190(2)(i), only a second or subsequent offence is listed. Civil penalties and criminal offences have different consequences, and exclusion from Section 200 alone does not make a civil penalty a criminal prosecution.
What to do if you have been fined
- Read the section on the challan, then read the section. An alteration charge, a tint charge and a silencer charge are three different cases with three different defences.
- Pull your registration certificate and compare particulars. Where the alleged alteration has not changed any registered particular, that is the argument, and it is a documentary one.
- Where the change is one the Act permits, produce the approval. A conversion kit fitment or an adapted vehicle conversion carried out with the registering authority's approval is answered by the paperwork, not by explanation.
- Where the change is not permitted, reverse it and get the record corrected. Section 52(3) contemplates the alteration being reported and the particulars entered, and a vehicle whose record has been squared is a vehicle that stops attracting repeat challans.
- Do not pay while you intend to contest. Check the payment and objection route, as our note on disputing an e-challan in Bengaluru explains.
One boundary is worth stating plainly, because it is often asserted at the roadside and is wrong. An alteration is not a ground to take the vehicle. Section 207 confines seizure and detention to contraventions of the licence, minimum age, registration and permit requirements. Where a vehicle has nonetheless been detained, the release routes are in our note on getting a seized vehicle released in Karnataka.