Nice thread, I can think of some mods to make a car more highway friendly. Lets keep this thread generic and not focussed on any particular model.
• Retain the OEM wheel size. Never upsize the wheels from stock (unlike what you've already done to your car). On Indian highways & in rural areas, you'll frequently encounter broken roads, unmarked speed breakers & the like. That additional sidewall height will definitely help your back & your car's suspension. In fact, for some stiffly sprung cars (e.g. SX4), downsizing the wheels from 16" to 15" is a fabulous idea.
• Tyres. High quality tyres in top shape can mean the difference between life & death. Also, if your car has tyres that are too thin, get an upsize (tyres only, not wheels).
• Comfortable seats : Supportive seats with a firmer compound are preferred over the really soft, unsupportive type. German cars have the best seats. It's easy to improve seat comfort from an after-market upholstery specialist.
• Center armrest for the driver is a must-have.
• Dead pedal. Best fitted at the factory level though.
• If you drive a car that handles poorly, look at after-market suspension options from reputable brands (of course, you need to own a car that has ready after-market support). However, you need something with balance, and not a solution that'll result in a bone-jarring ride.
• Similar to point no. 5, but for brakes.
• Some UVs have extremely short gearing that's a pain on the highway. When I changed the final drive of my Classic to 4.2, it resulted in a noticeable improvement on the open road.
• REMOVE loud free-flow exhaust & air intake.
• If you drive a car with mediocre power on tap, consider simple + reliable after-market options. Example : A power box for the Figo Diesel.
• Consider damping your car. Less exterior & mechanical noise will make the long drive stress free.
• Car specific updates due to design defects. E.g. coil spring adjusters for the Civic (sagging rear suspension), oil sump protection (Optra has a notorious rep for leaking sumps) etc.
• Powerful headlamps. Upgrade if necessary.
• Powerful horn. Fortunately or unfortunately, the horn remains a crucial safety device in India.
• Sunfilm that's effective (protection from the hot sun) and really light (so you don't get in trouble with the cops).
• 12v power socket & smartphone charger.
• Good ICE. I can't travel long-distance without good music.
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