Weird queston...

[niky]

When calculating payload, consider the weight of the car as part of the equation.

A small engine will be stressed and not-so-fuel efficient if the payload is too high. But that depends on how small the engine, how big the load, how efficient the transmission and how heavy the car is. A 1.0 engine pulling a lightweight Spark with a manual transmission and four passengers on board is not stressed... As long as you don't go mountain climbing, fuel economy will stay good.

But a 1.3 liter engine carrying just four passengers, put inside the heavier Honda Jazz with an automatic, will not be as efficient. Not that the 1.5 is any more efficient... The new Jazz is a big and heavy car. This is not to say the car can't serve you for the next ten years carrying that load... Because it can... Just that it isn't as fuel efficient as it can be. The only time you have to worry about 1.6 and under engines is when they're connected to rear wheel drive, like in the Avanza 1.3 and the automatic APV.

But this is worry in terms of economy. If you're worried about engine breakage... That's not going to happen with a modern 800cc to 1.4 liter engine unless you're hauling ten passengers up a mountainside in summer heat in crawling traffic. And even then, it would take years of such abuse, daily to make a dent.

I used to have a 1.3 liter full sedan. Beaten to high heaven and driven at up to 180 km/h with four on board. Survived for years with no issue. I've driven test units with 800cc engines. I've driven an 800cc Alto with four on board, and an Eon up a mountain. I drove a 1.2 liter Rio to the airport and picked up three people and 100 kilograms of luggage (about 600-700 kg total). Drove perfectly fine on the Skyway at 120. No problems climbing, whatsoever. The rear end didn't even sag, as Vios rear ends tend to do with a full trunk (and the Vios trunk is smaller) The only time I've ever felt a new car was too underpowered or stressed to carry four passengers was when I drove a 250cc three-wheeler with four doors. But, come on... That was a 16 horsepower engine...

When people say less than 1.8 is not enough, it just means they're impatient and want a faster car.

-

In terms of comfort... Absolute minimum for four people. Alto. Absolute minimum that's comfortable? If your rear passengers are girls... typically under 5'3", puwede Eon. These two can get you 13-15 kml in traffic with a full load... And 25 kml on the highway. If they're medium height guys, a Picanto or Spark 1.0 would do. About 10-11 in mixed traffic, just 15s on the highway for the Picanto... But I'm hearing 20 is possible with the Spark 1.0 MT. They're heavier than the Eon, which is why they're not as efficient. If they're tall guys, you're looking at City, Accent or Rio level. The Fiesta, Mazda2 and Vios all have smallish back seats. Typically 1.3 to 1.4 liter variants will do around 8-10 in traffic... With automatics, worse.

Rio 1.2 is least engine in the most car. Fuel economy is decent when going straight, but suffers in traffic, where it's only as good as the 1.4s and 1.5s. This is because it's heavy, but so far, it's the best car I've driven brand new for under 600k bucks. Bar none. Don't get the 1.4 AT. Sluggish 4-speed and economy is just so-so. About on par with 1.6 AT competitors... Actually, I think the Fiesta 1.6 AT might be more efficient.